DETAILED ACTION
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 12/17/2025 has been entered.
Response to Arguments
Applicant's arguments filed on 12/17/2025 have been fully considered but they are moot because a new ground(s) of rejection is made in view of Nakajima et al (US 2009/0190921).
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-3, 16-18 and 22 are rejected under 35 U.S.C. 103 as being unpatentable over Smith et al (US 2008/0031624) in view of Minami et al (US 6,310,702) and Daems (US 2011/0268438) and Nakajima et al (US 2009/0190921).
1). With regard to claim 1, Smith et al discloses an optical fiber monitoring apparatus (Figure 1, the combination of OTDR 10, splitters 14/16 and fibers connecting the splitters etc.) comprising:
an optical time domain reflectometer (OTDR) (OTDR 10, [0007]-[0010], or the combination of OTDR and the splitter 14), wherein the OTDR is optically connected to N optical fibers (Figure 1, e.g., the splitter 16 is connected to 8 optical fibers, [0008]), wherein N is greater than one (e.g., N is 8); and
a 1 x N optical splitter (one of the 1 x 8 splitters 16) that is optically connected to the OTDR (Figure 1),
wherein N is greater than one (e.g., 1 x 8 splitter, [0008]),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (e.g., 8 test port optical fiber outputs for 8 fibers, and the fibers are connected to ONT 18), and
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Figure O1
wherein the OTDR is a simultaneous multi-channel OTDR (Figure O1 above, which is adapted from Smith’s Figure 1, and the dotted box is added to show the structure corresponding to claimed “multi-channel OTDR”) having multiple, parallel inputs/outputs (e.g., the eight inputs/outputs associated with the splitter 14) each coupled through a dedicated optical fiber (one of the eight fibers, each between the splitter 14 and one splitter 16) to one of a plurality of 1 x N independent splitters (one of the eight 1x8 independent splitters 16), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (any one of the 1 x N optical splitter is one of the eight 1 x 8 optical splitters 16), and further wherein each test port optical fiber output (any one of the eight outputs from the splitters 16 (at the right side of splitter 16)) is optically connectable to an optical fiber (one of the fibers between the splitters 16 and ONTs 18) to optically connect the optical fiber to the OTDR (via the fibers and splitters 16 and splitter 14) for simultaneous monitoring of each test port optical fiber output by the OTDR ([0007]-[0010]).
But, Smith et al does not expressly disclose: each of the N optical fibers has dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers, and wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate to implement a plurality of splitting ratios.
Regarding the reflectors, however, to implement dedicated reflectors at the ends of optical fibers are well known in the art so to get a baseline power levels or attenuations. E.g., Minami et al discloses a testing apparatus (Figure 1 etc.) for simultaneous monitoring of each test port optical fiber (C1, C2, D1, D2 and D3) by an OTDR (Figures 2 and 5 etc.). As shown in Figure 1 of Minami et al, each optical fiber has a dedicated reflector (EC1, EC2, ED1, ED2 and ED3); and “FIG. 2 is a graph showing a response waveform representing response light containing reflection beams and back scattering beams, which are measured by an OTDR measurement device shown in FIG. 1 before occurrence of fault” (column 3 lines 16-19); “a vertical axis of FIG. 2 represents a level of the response light which is a mixture of the reflection beams and back scattering beams given from the optical fibers A to D3 respectively. A spike wave emerges at each of points of the waveform of FIG. 2 which correspond to the terminal points EC1, EC2, ED1, ED2 and ED3 of the optical fibers C1, C2, D1, D2 and D3 respectively. This spike wave is produced based on Fresnel reflection. The terminal point EC1 is located optically in the closest proximity to the OTDR measurement device MS1. So, other terminal points are located with different distances from the OTDR measurement device MS1, wherein locations of them become farther from the device MS1 in an order of ED1, ED2, ED3 and EC2. That is, the terminal point EC2 is located at the farthest place from the device MS1” (column 4 lines 49-64); “With regard to record events that are recorded in connection with the measurement times lying between t1 and tk, there occurs no change in optical power, so it is possible to make a decision that an abnormal state does not exist. With regard to record events that are recorded in connection with the measurement times of tk and tk+1, a change occurs in optical power, so it is possible to make a decision that an abnormal state exists. Based on the time that the abnormal state occurs, it is possible to calculate a fault distance (or fault location) with ease”. That is, Fig. 2 is an initial measurement, and is a baseline to be compared when any other events occur. As shown in Figure 5, an event “ED2’ ” occurs. Following Figure O2 shows the comparison between Minami’s Figure 2 and Figure 5.
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Figure O2
As shown in Figure O2 above, “the location of the terminal point ED2 of the optical fiber D2 on the waveform (see FIG. 2), which is measured at the time tk, is shifted to a location of a terminal point ED2' on the waveform (see FIG. 5), which is measured at the time tk+1. So, it can be estimated that a fault occurs in an interval of time between tk and tk+1. In addition, a fault line on which the fault occurs matches with the optical fiber D2 whose terminal point is shifted as described above. Further, a fault distance matches with a shift distance by which the location of the terminal point ED2 at the time tk is shifted to the location of the terminal point ED2' at the time tk+1” (column 6 lines 19-44); Minami’s Figure 2 shows the measured power level (attenuation) of reflected signal vs fiber distance; the longer the fiber, the signal intensity is attenuated more; and when a fault occurs on fiber D2, the original signal ED2 is completed “attenuated” or disappeared, and a new signal at ED2’ comes; therefore, what are showed in Figure 2, which are measured “before occurrence of fault”, are calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers. Although Minami et al does not use the word “calibrated”, as discussed above, the processing to obtain the waveform shown in Figure 2 and the purpose/usage of Figure 2 are actually making the Figure 2 be “calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers”. Another prior art, Daems, also discloses a system/method for “ABSOLUTE OPTICAL ATTENUATION MEASUREMENT WITH OTDR” (title), and “Devices and methods for optical measurements in point-to-point and point-to-multipoint networks, e.g. like PON networks with splitters are described in which reflected power from some known reflections at the end of the lines is used to determine the attenuation and stability of the attenuation of each line” (Abstract). As shown in Figures 2 and 4 etc., reflectors (14 and 16 in Figure 2, or Ref R1 and Ref R2 in Figure 4; [0042]-[0045] and [0059] etc.) are implemented at the end of fibers, and “FIG. 4 shows how test equipment in accordance with the present invention can be calibrated” ([0029]) and “This calibration can be done when setting up the optical network. Once calibrated, the measurement of absolute loss can be done without further use of power meters” ([0059]); and “Accurate loss measurements are possible from just one side of the network through the splitter” ([0064]); and “It can be understood from the above that the measured absolute values of loss are obtained by methods and devices according to the present invention. As an extension of the present invention, the network can be monitored over time and changes in loss can be detected, e.g. as caused by a sharp bend introduced into a fiber. The measurement of absolute loss allows a change over time to be detected, whereas relative methods may suffer from changes in conditions between measurements which alter the result”; therefore, Daems teaches/suggests “dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”. In Figures 2 and 4, Daems uses the power level of the signal reflected from the retuning device 10 as a reference to calculate the “absolute loss” of each branch ([0049]-[0059]); and in Minami’s Figures 2 and 5, the power level of the signal reflected from the coupler CP1 is used as a reference to evaluate the signal levels/loss/attenuations of different fiber paths (Figure 2, at Distance 0 “CP1”, the power is normalized to “1”, or P/P0 is 1; and all other signal levels reflected from different paths/points are relative to or compared with the power level “1” reflected by CP1); then, the scheme or processes used for calculate a value representative of the absolute loss of each branch also can be applied to the system of combined Smith et al and Minami et al.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply dedicated reflectors at the ends of fibers as taught by Minami et al and Daems to the system/method of Smith et al so that a baseline or calibrated reference signal waveforms can be obtained, and fault events and position at faults can be accurately identified.
Regarding the splitters with a plurality of splitting ratios, first, for the embodiment of Figure 2 etc., Smith et al states “It will be apparent to those skilled in the art that various modifications and variations can be made to this invention without departing from the spirit or scope of the invention”; and Minami et al discloses a plurality of 1 x N optical splitters (Figure 1) with a plurality of splitting ratios (e.g., CP2 having 1:2 splitting ratio, and CP3 having a 1:3 splitting ratio). Second, Nakajima et al discloses an optical fiber monitoring system/method (Figures 1 and 22 etc.) comprising:
an optical time domain reflectometer (OTDR) (2 in Figure 1, [0170], “an OTDR (Optical Time Domain Reflectometer) is used as the test apparatus 2, and ONUs (Optical Network Units) are used as the terminators 4 is described”), wherein the OTDR is optically connected to N optical fibers (f5/f6, or f7-f9), each having dedicated reflectors (terminators 4a-4f etc. in Figures 1 and 5-7 etc., Abstract, and [0107]-[0113] etc.; e.g., fiber f5 has a reflector/terminator 4a, and fiber f6 has a reflector/terminator 4b. Figure 22, [0237], “the optical fiber lengths from the measurement apparatus 350 to the respective ONUs 420-1 to 420-N as the terminators are previously designed to be different when the optical fibers are deployed.”) connected to an end (Figures 1 and 5-7, terminator. Figure 22, the ONU) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (Abstract, and [0117]-[0122] etc., “In the normal information recording portion 14b, information with regard to intensities of the reflected lights which, after being emitted from the test apparatus 2 via the splitters 3, are reflected and returned by the respective terminators 4 is previously recorded. The intensities of the reflected lights recorded in this normal information recording portion 14b are those from the respective terminators 4 in the case where there is no failure in the optical lines f (f1 to f10)”, and “The attenuation amount determination portion 15 determines by how much the reflected light intensity of the predetermined terminator 4 previously recorded in the normal information recording portion 14b is attenuated from the corresponding reflected light intensity recorded in the monitored information recording portion 14c. Furthermore, the attenuation amount determination portion 15 determines whether or not the attenuated amount is equal in value to the attenuated amount of the other terminators 4 belonging to the same group”. And Figure 3, “one example of group information recorded in the group information recording portion 14a. As shown in the figure, information with regard to the terminators 4 connected to the same splitter 3 is recorded as group information, classified for every group. For example, the terminators 4a, 4b connected to the splitter 3b are recorded as in group g1”), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”); and
a 1 x N optical splitter (e.g., the splitter 3b in Figure 1, or 410 in Figure 22) that is optically connected to the OTDR (Figures 1 and 22 etc.), wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate ([0110], “As a splitter 3, for example a PLC (Planar Lightwave Circuit) type splitter can be used in which optical waveguides are branched in a tree-like manner on a silica substrate”, and [0184]) to implement a plurality of splitting ratios (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (e.g., the splitter 3b has two test port optical fiber outputs), and
wherein the OTDR is a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a forms a multi-channel OTDR, which has three parallel inputs/outputs associated with fibers f2, f3 and f4), having multiple parallel inputs/outputs (e.g., the three parallel inputs/outputs for the fibers f2-f4) each coupled through a dedicated optical fiber (one of the f2, f3, or f4) to one of a plurality of 1 x N independent splitters (3b-3d in Figure 1 etc.), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., the splitter 3b), and further wherein each test port optical fiber output is optically connectable to an optical fiber (e.g., the two test ports of the splitter 3b is optically connectable to two optical fibers f5 and f6, respectively) to optically connect the optical fiber to the OTDR for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 1 and 5-7 etc. and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the splitter arrangement as taught by Nakajima et al to the system/method of Smith et al and Minami et al and Daems so that a compact, high reliable, excellent uniform (even power split), low wavelength dependent splitting assembly (having a plurality of splitters) can be obtained, and the splitting assembly is highly scalable to many channels.
2). With regard to claim 2, Smith et al and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claim 1 above. And the combination of Smith et al and Minami et al and Daems and Nakajima et al further discloses wherein the OTDR is optically connected to N optical fibers including the optical fiber to extract, from each optical fiber of the N optical fibers, information by analyzing signals returned from the N optical fibers to the N test port optical fiber outputs (Smith: [0007]-[0010], “An OTDR analyzes the light loss in an optical fiber by transmitting a (laser) light pulse into the optical fiber and measuring the backscatter and reflection of light as a function of time. The reflected light characteristics are analyzed to determine the location of any broken or damaged fibers, faulty connectors, splice losses, or other faults”. Minami: Figures 2-6 etc. Nakajima: Figures 4, 11-12 and 16 etc.).
3). With regard to claim 3, Smith et al and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claim 1 above. And the combination of Smith et al and Minami et al and Daems and Nakajima et al further discloses wherein the OTDR is optically connected to N optical fibers including the optical fiber to compare, for the N optical fibers, N simultaneous test results to a reference test result to identify changes on at least one optical fiber under test of the N optical fibers (Minami: as discussed in claim 1 rejection, Figure 2 is a reference test result waveform or baseline, and Figure 5 shows ED2’ peak, which is due to “ED2 … is shifted to a location of a terminal point ED2' on the waveform”, and “a fault distance matches with a shift distance by which the location of the terminal point ED2 at the time tk is shifted to the location of the terminal point ED2' at the time tk+1” column 6 lines 18-44; “the fault determination is made by comparing results of the separative analysis, which are obtained at the measuring times respectively. By the fault determination, it is possible to determine a fault line and a fault location (or fault distance) as well as a fault time” column 2 line 64 to column 3 line 3. Nakajima: Figures 1, 4-7, 11-12 and 16 etc.).
4). With regard to claim 16, Smith et al discloses an optical fiber monitoring apparatus (Figure 1, the combination of OTDR 10, splitters 14/16 and fibers connecting the splitters etc.) comprising:
an optical time domain reflectometer (OTDR) (OTDR 10, [0007]-[0010], or the combination of OTDR and the splitter 14), wherein the OTDR is optically connected to N optical fibers (Figure 1, e.g., the splitter 16 is connected to 8 optical fibers, [0008]), wherein N is greater than one (e.g., N is 8), wherein the OTDR is a simultaneous multi-channel OTDR (Figure O1 above, which is adapted from Smith’s Figure 1, and the dotted box is added to show the structure corresponding to claimed “multi-channel OTDR”) having multiple, parallel inputs/outputs (e.g., the eight inputs/outputs associated with the splitter 14) each coupled through a dedicated optical fiber (one of the eight fibers, each between the splitter 14 and one splitter 16) to one of a plurality of 1 x N independent splitters (one of the eight 1x8 independent splitters 16); and
a 1 x N optical splitter (one of the splitters 16) that is optically connected to the OTDR to test at least one optical fiber of N optical fibers (fibers between the splitters 16 and ONTs 18) that are optically connected to the 1 x N optical splitter (splitter 16), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (any one of the 1 x N optical splitter is one of the eight 1 x 8 optical splitters 16),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (each splitter 16 has eight outputs (at the right side of splitter 16)) for simultaneous monitoring of each test port optical fiber output by the OTDR ([0007]-[0010]),
wherein N is greater than one (Figure 1, or Figure O1 above, 1:8 splitters 16; or N = 8).
But, Smith et al does not expressly disclose: each of the N optical fibers has dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers, and wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate to implement a plurality of splitting ratios.
Regarding the reflectors, however, to implement dedicated reflectors at the ends of optical fibers are well known in the art so to get a baseline power levels or attenuations. E.g., Minami et al discloses a testing apparatus (Figure 1 etc.) for simultaneous monitoring of each test port optical fiber (C1, C2, D1, D2 and D3) by an OTDR (Figures 2 and 5 etc.). As shown in Figure 1 of Minami et al, each optical fiber has a dedicated reflector (EC1, EC2, ED1, ED2 and ED3); and “FIG. 2 is a graph showing a response waveform representing response light containing reflection beams and back scattering beams, which are measured by an OTDR measurement device shown in FIG. 1 before occurrence of fault” (column 3 lines 16-19); “a vertical axis of FIG. 2 represents a level of the response light which is a mixture of the reflection beams and back scattering beams given from the optical fibers A to D3 respectively. A spike wave emerges at each of points of the waveform of FIG. 2 which correspond to the terminal points EC1, EC2, ED1, ED2 and ED3 of the optical fibers C1, C2, D1, D2 and D3 respectively. This spike wave is produced based on Fresnel reflection. The terminal point EC1 is located optically in the closest proximity to the OTDR measurement device MS1. So, other terminal points are located with different distances from the OTDR measurement device MS1, wherein locations of them become farther from the device MS1 in an order of ED1, ED2, ED3 and EC2. That is, the terminal point EC2 is located at the farthest place from the device MS1” (column 4 lines 49-64); “With regard to record events that are recorded in connection with the measurement times lying between t1 and tk, there occurs no change in optical power, so it is possible to make a decision that an abnormal state does not exist. With regard to record events that are recorded in connection with the measurement times of tk and tk+1, a change occurs in optical power, so it is possible to make a decision that an abnormal state exists. Based on the time that the abnormal state occurs, it is possible to calculate a fault distance (or fault location) with ease”. That is, Fig. 2 is an initial measurement, and is a baseline to be compared when any other events occur. As shown in Figure 5, an event “ED2’ ” occurs. Figure O2 above shows the comparison between Minami’s Figure 2 and Figure 5.
As shown in Figure O2 above, “the location of the terminal point ED2 of the optical fiber D2 on the waveform (see FIG. 2), which is measured at the time tk, is shifted to a location of a terminal point ED2' on the waveform (see FIG. 5), which is measured at the time tk+1. So, it can be estimated that a fault occurs in an interval of time between tk and tk+1. In addition, a fault line on which the fault occurs matches with the optical fiber D2 whose terminal point is shifted as described above. Further, a fault distance matches with a shift distance by which the location of the terminal point ED2 at the time tk is shifted to the location of the terminal point ED2' at the time tk+1” (column 6 lines 19-44); Minami’s Figure 2 shows the measured power level (attenuation) of reflected signal vs fiber distance; the longer the fiber, the signal intensity is attenuated more; and when a fault occurs on fiber D2, the original signal ED2 is completed “attenuated” or disappeared, and a new signal at ED2’ comes; therefore, what are showed in Figure 2, which are measured “before occurrence of fault”, are calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers. Although Minami et al does not use the word “calibrated”, as discussed above, the processing to obtain the waveform shown in Figure 2 and the purpose/usage of Figure 2 are actually making the Figure 2 be “calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers”. Another prior art, Daems, also discloses a system/method for “ABSOLUTE OPTICAL ATTENUATION MEASUREMENT WITH OTDR” (title), and “Devices and methods for optical measurements in point-to-point and point-to-multipoint networks, e.g. like PON networks with splitters are described in which reflected power from some known reflections at the end of the lines is used to determine the attenuation and stability of the attenuation of each line” (Abstract). As shown in Figures 2 and 4 etc., reflectors (14 and 16 in Figure 2, or Ref R1 and Ref R2 in Figure 4; [0042]-[0045] and [0059] etc.) are implemented at the end of fibers, and “FIG. 4 shows how test equipment in accordance with the present invention can be calibrated” ([0029]) and “This calibration can be done when setting up the optical network. Once calibrated, the measurement of absolute loss can be done without further use of power meters” ([0059]); and “Accurate loss measurements are possible from just one side of the network through the splitter” ([0064]); and “It can be understood from the above that the measured absolute values of loss are obtained by methods and devices according to the present invention. As an extension of the present invention, the network can be monitored over time and changes in loss can be detected, e.g. as caused by a sharp bend introduced into a fiber. The measurement of absolute loss allows a change over time to be detected, whereas relative methods may suffer from changes in conditions between measurements which alter the result”; therefore, Daems teaches/suggests “dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”. In Figures 2 and 4, Daems uses the power level of the signal reflected from the retuning device 10 as a reference to calculate the “absolute loss” of each branch ([0049]-[0059]); and in Minami’s Figures 2 and 5, the power level of the signal reflected from the coupler CP1 is used as a reference to evaluate the signal levels/loss/attenuations of different fiber paths (Figure 2, at Distance 0 “CP1”, the power is normalized to “1”, or P/P0 is 1; and all other signal levels reflected from different paths/points are relative to or compared with the power level “1” reflected by CP1); then, the scheme or processes used for calculate a value representative of the absolute loss of each branch also can be applied to the system of combined Smith et al and Minami et al.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply dedicated reflectors at the ends of fibers as taught by Minami et al and Daems to the system/method of Smith et al so that a baseline or calibrated reference signal waveforms can be obtained, and fault events and position at faults can be accurately identified.
Regarding the splitters with a plurality of splitting ratios, first, for the embodiment of Figure 2 etc., Smith et al states “It will be apparent to those skilled in the art that various modifications and variations can be made to this invention without departing from the spirit or scope of the invention”; and Minami et al discloses a plurality of 1 x N optical splitters (Figure 1) with a plurality of splitting ratios (e.g., CP2 having 1:2 splitting ratio, and CP3 having a 1:3 splitting ratio). Second, Nakajima et al discloses an optical fiber monitoring system/method (Figures 1 and 22 etc.) comprising:
an optical time domain reflectometer (OTDR) (2 in Figure 1, [0170], “an OTDR (Optical Time Domain Reflectometer) is used as the test apparatus 2, and ONUs (Optical Network Units) are used as the terminators 4 is described”), wherein the OTDR is optically connected to N optical fibers (f5/f6, or f7-f9), each having dedicated reflectors (terminators 4a-4f etc. in Figures 1 and 5-7 etc., Abstract, and [0107]-[0113] etc.; e.g., fiber f5 has a reflector/terminator 4a, and fiber f6 has a reflector/terminator 4b. Figure 22, [0237], “the optical fiber lengths from the measurement apparatus 350 to the respective ONUs 420-1 to 420-N as the terminators are previously designed to be different when the optical fibers are deployed.”) connected to an end (Figures 1 and 5-7, terminator. Figure 22, the ONU) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (Abstract, and [0117]-[0122] etc., “In the normal information recording portion 14b, information with regard to intensities of the reflected lights which, after being emitted from the test apparatus 2 via the splitters 3, are reflected and returned by the respective terminators 4 is previously recorded. The intensities of the reflected lights recorded in this normal information recording portion 14b are those from the respective terminators 4 in the case where there is no failure in the optical lines f (f1 to f10)”, and “The attenuation amount determination portion 15 determines by how much the reflected light intensity of the predetermined terminator 4 previously recorded in the normal information recording portion 14b is attenuated from the corresponding reflected light intensity recorded in the monitored information recording portion 14c. Furthermore, the attenuation amount determination portion 15 determines whether or not the attenuated amount is equal in value to the attenuated amount of the other terminators 4 belonging to the same group”. And Figure 3, “one example of group information recorded in the group information recording portion 14a. As shown in the figure, information with regard to the terminators 4 connected to the same splitter 3 is recorded as group information, classified for every group. For example, the terminators 4a, 4b connected to the splitter 3b are recorded as in group g1”), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”), wherein the OTDR is a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a forms a multi-channel OTDR, which has three parallel inputs/outputs associated with fibers f2, f3 and f4), having multiple parallel inputs/outputs (e.g., the three parallel inputs/outputs for the fibers f2-f4) each coupled through a dedicated optical fiber (one of the f2, f3, or f4) to one of a plurality of 1 x N independent splitters (splitters 3b-3d in Figure 1 etc.),
a 1 x N optical splitter (e.g., the splitter 3b in Figure 1, or 410 in Figure 22) that is optically connected to the OTDR (Figures 1 and 22 etc.) to test at least one optical fiber of N optical fibers that are optically connected to the 1x N optical splitter (Figures 4, 11-12 and 16 etc.; and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., the splitter 3b), wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate ([0110], “As a splitter 3, for example a PLC (Planar Lightwave Circuit) type splitter can be used in which optical waveguides are branched in a tree-like manner on a silica substrate”, and [0184]) to implement a plurality of splitting ratios (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (e.g., the splitter 3b has two test port optical fiber outputs) for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 1 and 5-7 etc. and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”),
wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the splitter arrangement as taught by Nakajima et al to the system/method of Smith et al and Minami et al and Daems so that a compact, high reliable, excellent uniform (even power split), low wavelength dependent splitting assembly (having a plurality of splitters) can be obtained, and the splitting assembly is highly scalable to many channels.
5). With regard to claim 17, Smith et al and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claim 16 above. And the combination of Smith et al and Minami et al and Daems and Nakajima et al further discloses wherein the OTDR is optically connected to the N optical fibers to extract, from each optical fiber of the N optical fibers, information by analyzing signals returned from the N optical fibers (Smith: [0007]-[0010], “An OTDR analyzes the light loss in an optical fiber by transmitting a (laser) light pulse into the optical fiber and measuring the backscatter and reflection of light as a function of time. The reflected light characteristics are analyzed to determine the location of any broken or damaged fibers, faulty connectors, splice losses, or other faults”. Minami: Figures 2-6 etc. Nakajima: Figures 4, 11-12 and 16 etc.).
6). With regard to claim 18, Smith et al and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claim 16 above. And the combination of Smith et al and Minami et al and Daems and Nakajima et al further discloses wherein the OTDR is optically connected to N optical fibers including the optical fiber to compare, for the N optical fibers, N simultaneous test results to a reference test result to identify changes on at least one optical fiber under test of the N optical fibers (Minami: as discussed in claim 16 rejection, Figure 2 is a reference test result waveform or baseline, and Figure 5 shows ED2’ peak, which is due to “ED2 … is shifted to a location of a terminal point ED2' on the waveform”, and “a fault distance matches with a shift distance by which the location of the terminal point ED2 at the time tk is shifted to the location of the terminal point ED2' at the time tk+1” column 6 lines 18-44; “the fault determination is made by comparing results of the separative analysis, which are obtained at the measuring times respectively. By the fault determination, it is possible to determine a fault line and a fault location (or fault distance) as well as a fault time” column 2 line 64 to column 3 line 3. Nakajima: Figures 1, 4-7, 11-12 and 16 etc.).
7). With regard to claim 22, Smith et al and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claim 16 above. And the combination of Smith et al and Minami et al and Daems and Nakajima et al further discloses wherein the OTDR operates at a different wavelength than a traffic wavelength (in Figure 1, Smith does not expressly state that the OTDR operates at a different wavelength than a traffic wavelength; however for the embodiment shown in Figure 2, Smith discloses “it is preferred that OTDR system 20 transmit a wavelength that does not interfere with the wavelengths on which OLT 22 operates. By operating OTDR system 20 and OLT 22 on non-interfering wavelengths, OTDR system 20 can be used to troubleshoot the network or portions thereof without interfering with normal network communication between OLT 22 and ONTs 28”, [0020] and [0024]. Daems also discloses “a separate optical test equipment 8 is provided, such as an OTDR, that operates at a different wavelength (for example the test equipment 8 operates at a wavelength of 1625 nm) than the service equipment 2 (e.g. that operates at 1490, 1550 nm when the network is operational)”, [0044]-[0045]. Nakajima: [0239], “The directional coupler 400 performs multiplexing/demultiplexing with wavelength dependency to multiplex communication light incident from the transmission apparatus 390 via the optical fiber 330 and an optical pulse from the measurement apparatus 350 which is incident from the optical switch 340 via the optical fiber 500-1, and outputs the multiplexed communication light and optical pulse to the optical fiber 360”; that is, the OTDR operates at a different wavelength than a traffic wavelength).
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Smith et al and Minami et al and Daems and Nakajima et al as applied to claim 1 above, and in further view of Perry (US 2023/0013084).
Smith et al and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claim 1 above. But, Smith et al and Minami et al and Daems and Nakajima et al do not expressly disclose the optical fiber monitoring apparatus according to claim 1, further comprising: N optical fibers of different lengths optically inserted between the N test port optical fiber outputs and N optical fibers including the optical fiber, wherein the N optical fibers are optically connected to the N test port optical fiber outputs.
However, to introduce N delay fibers into the transmission paths for OTDR is a common practice. E.g., Perry discloses a system/method to monitor optical fibers. As shown in Figure 2F, 4 optical fibers of different lengths (287a-287d) optically inserted between a N test port optical fiber outputs (splitter multi ports) and N optical fibers (284a-284d) including the optical fiber (284), wherein the N optical fibers are optically connected to the N test port optical fiber outputs (Figure 2F).
It is also worth to point out that Perry also discloses that dedicated reflectors are implemented at the end of each fiber (Figure 1: at the End Equip 207; Figure 2F: the terminating connectors 289); “installation and/or maintenance teams dispatched to the field for installation and/or maintenance may conduct supplemental OTDR measurements on the entire PON 211 and/or segments of the PON 211, such as the first optical fiber 202 and/or the distal optical fibers 206. Results, including cable lengths, may be stored and/or otherwise retained in PON configuration records. Similarly, the timing offsets of the output ports 205 of the splitter 203 may be measured and/or otherwise determined according to specification sheets, calibration records, manufacturing records, and the like” ([0059]); “the timing offset values may be determined at a time of manufacture, e.g., curing a characterization or performance test and/or calibration procedure.” ([0075]); “It is understood that a device characterization and/or calibration procedure by which the delay values are determined may be performed at a time of manufacture and/or at a time of installation or perhaps even post installation. For example, a test pulse may be injected into the input, e.g., port 0, and divided into four pulse signal segments, one at each of the output ports, e.g., ports 1-4. A time difference may be measured and/or otherwise calculated based on measured time differences between injection of the input test pulse and detective of the respective output test pulses. The resulting delay measurements may be recorded and/or otherwise noted, e.g., in association with the particular optical splitter device serial number, to the extent the results may vary from device to device” ([0090]); as shown in Figure 2B, “The example OTDR trace 227 represents a graphical signature of an optical fiber network, e.g., PON 211 (FIG. 2A). The trace 227 indicates attenuation along a length of the optical fiber, which provides insight into the performance of the link components (cable, connectors, and splices) and the quality of an installation by examining non-uniformities in the OTDR trace 220” ([0053]-[0054]); and “According to the illustrative PON 211, the fourth, fifth and sixth events 223d, 223e, 223f correspond to fiber terminations at the ONTs 207” ([0058]); and then Figure 2C shows “The example trace 237 is presented as a graph with magnitude along a vertical axis 231 and time along a horizontal axis 232. In particular, the trace 237 represents a trace obtained from the same PON 211, to permit a comparison to the initial trace 227 (FIG. 2B) obtained during normal operating conditions, e.g., at a time of installation and/or reconfiguration. Any changes to the PON 211 that may result from breaks, bends, stretches and/or configuration changes, are observable as differences between the initial trace 227 and the example subsequent trace 237” ([0063]); therefore, Figure 2B of Perry is also “calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”; as shown in Figure 2C, the original event 233e “does not appear in the subsequent trace 237”, instead a new event 236 comes.
As disclosed by Perry, “The optical delay devices provide distinguishable delay values, that delay the divided portions of the optical signal, the distinguishable delay values facilitating associations of the PON segments to the output ports based on optical time domain reflectometry (OTDR) measurements obtained via the input port” (Abstract, and [0089]-[0096]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use fiber delays as taught by Perry to the system/method of Smith et al and Minami et al and Daems and Nakajima et al so that distinguishable delay values/events can be obtained and identified, and coincidence of reflected pulses from different fibers under test can be avoided.
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Smith et al and Minami et al and Daems and Nakajima et al as applied to claim 1 above, and in further view of Perry (US 2023/0013084) and Martel et al (US 2020/0252125).
Smith et al and Minami et al and Daems and Nakajima et al discloses all of the subject matter as applied to claim 1 above. And Smith et al and Minami et al and Daems and Nakajima et al disclose wherein the N optical fibers are optically connected to the N test port optical fiber outputs (Lam: Figure 3 and Figure 6. Figure 1 of Minami, Figure 1 of Smith. Nakajima: Figures 1, 5-7 and 22).
But, Smith et al and Minami et al and Daems and Nakajima et al do not expressly disclose the optical fiber monitoring apparatus according to claim 1, further comprising: N antennas connected to N optical fibers including the optical fiber.
However, it is obvious to one skilled in the art that the system/method disclosed by Smith et al and Minami et al and Daems and Nakajima et al can be used for Radio-over-Fiber (RoF) system/method, in which antennas are connected to optical fibers, respectively. E.g., Perry discloses a multi-path OTDR system (Figure 2A) functioning within the communication network of Figure 1 ([0007] and [0039]); and Figure 1 can be the distributed antennas networks ([0161], “the distributed antennas networks shown in FIG. 1(s) that enhance wireless service coverage by providing more network coverage”, and [0035]), and the end equipment can be antennas (e.g., 122 in Figure 1). Another prior art, Martel et al, also discloses a system/method in which N antennas connected to N optical fibers (Figure 1, and [0024]-[0028] etc., “send an optical probe signal to the particular RRH 12, 14, 16 and receive a back-reflected signal to perform fiber monitoring testing (e.g., OTDR)”, the RRH 12/14/16 are remote radio head, or antenna).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Perry and Martel et al to the system/method of Smith et al and Minami et al and Daems and Nakajima et al so that the OTDR can be used to monitor the radio-over-fiber system.
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Smith et al (Smith ‘624) and Minami et al and Daems and Nakajima et al as applied to claim 1 above, and further in view of Smith et al (US 2013/0259469. Hereinafter Smith ‘469) and Kim et al (US 2011/0026923).
Smith ‘624 and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claim 1 above. But, Smith ‘624 and Minami et al and Daems and Nakajima et al do not expressly disclose wherein the OTDR is a multi-wavelength OTDR, further comprising: a multi-wavelength multiplexer/demultiplexer optically inserted between the OTDR and the plurality of 1 x N independent splitters.
However, an OTDR that outputs a plurality of wavelength is known in the art. E.g., Smith ‘469 discloses a system/method to monitor a passive optical network (PON). As shown in Figures 4-6, an OTDR can send multiple wavelengths; and a multi-wavelength multiplexer/demultiplexer (e.g., 510) can be used to demultiplex the output from the OTDR and multiplex reflected signals from the fibers under test. In Figure 5, Smith ‘469 does not expressly show a plurality of splitters connected to the output ports of the multiplexer/demultiplexer (e.g., 510/515). However, fist, the references Smith ‘624 and Minami et al and Nakajima et al discloses that a splitter can be inserted between the OTDR and a plurality of 1 x N splitters. Second, another prior art, Kim et al, discloses a WDM-TDM-PON (Figures 2 and 23 etc.), as shown in Figures 2 and 23, optical splitters (205 in Figure 2, or the 1:M splitters in Figure 23) are connected to a multi-wavelength multiplexer/demultiplexer (Muc/Demux). By using the WDM-TDM structure with splitters, the optical line terminal (OLT) can reach more ONUs or clients grouped by splitters. And Kim et al also discloses that a monitoring structure similar to the OTDR can be installed in the OLT (Figures 27 and 29), as shown in Figure 29, a plurality of wavelengths are outputs from the multiplexer 2665 and sent downstream for monitoring fibers.
By using different wavelengths and each splitter associating with one wavelength, reflected pulses on different wavelengths, which arrive the detector at the same time, are distinguishable due to their different wavelengths. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Smith ‘469 and Kim et al to the system/method of Smith ‘624 and Minami et al and Daems and Nakajima et al so that a multiplexer/demultiplexer, instead of a splitter, is used between the OTDR and the plurality of 1 x N splitters, and a WDM-TDM OTDR (WDM+Splitters) can be obtained and the functions of the system/method is enhanced.
Claims 9 and 23 are rejected under 35 U.S.C. 103 as being unpatentable over Smith et al and Minami et al and Daems and Nakajima et al as applied to claims 1 and 16 above, and in further view of Lam et al (US 9,240,855).
1). With regard to claim 9, Smith et al and Minami et al and Daems and Nakajima et al discloses all of the subject matter as applied to claim 1 above. And the combination of Smith et al and Minami et al and Daems and Nakajima et al disclose wherein the OTDR operates at a different wavelength than a traffic wavelength (in Figure 1, Smith does not expressly state that the OTDR operates at a different wavelength than a traffic wavelength; however, for the embodiment shown in Figure 2, Smith discloses “it is preferred that OTDR system 20 transmit a wavelength that does not interfere with the wavelengths on which OLT 22 operates. By operating OTDR system 20 and OLT 22 on non-interfering wavelengths, OTDR system 20 can be used to troubleshoot the network or portions thereof without interfering with normal network communication between OLT 22 and ONTs 28”, [0020] and [0024]. Daems also discloses “a separate optical test equipment 8 is provided, such as an OTDR, that operates at a different wavelength (for example the test equipment 8 operates at a wavelength of 1625 nm) than the service equipment 2 (e.g. that operates at 1490, 1550 nm when the network is operational)”, [0044]-[0045]. Nakajima: Figure 22, [0239], “The directional coupler 400 performs multiplexing/demultiplexing with wavelength dependency to multiplex communication light incident from the transmission apparatus 390 via the optical fiber 330 and an optical pulse from the measurement apparatus 350 which is incident from the optical switch 340 via the optical fiber 500-1, and outputs the multiplexed communication light and optical pulse to the optical fiber 360”; that is, the OTDR operates at a different wavelength than a traffic wavelength), further comprising: a wavelength dependent multiplexer (e.g., the WDM 4 in Figure 2 of Daems. Nakajima: WDM 400 in Figure 22) to insert a test signal on the optical fiber.
But, in Figure 2 of Daems, the wavelength dependent multiplexer (WDM 4) is on the leading fiber (22), not on the fibers (24) after the splitter 12.
However, Lam et al discloses an optical fiber monitoring apparatus (Figures 1-3 and 6); wherein the OTDR operates at a different wavelength (wavelength associated with OTDR 135) than a traffic wavelength (Lam: wavelengths associated with the OLT TX/RX 125; column 4 lines 50-56), further comprising: a wavelength dependent multiplexer (Lam: e.g., wavelength selective 3-port optical couplers 210) to insert a test signal on the optical fiber (145 in Figure 3; or 210 in Figures 2 and 6).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Lam et al to the system/method of Smith et al and Minami et al and Daems and Nakajima et al so that the test/monitoring signals and the data traffic can be properly sent to the desired destination without interference.
2). With regard to claim 23, Smith et al and Minami et al and Daems and Nakajima et al discloses all of the subject matter as applied to claim 16 above. And the combination of Smith et al and Minami et al and Daems and Nakajima et al disclose the optical fiber monitoring apparatus according to claim 16, further comprising a wavelength dependent multiplexer to insert a test signal (e.g., the WDM 4 in Figure 2 of Daems. Nakajima: WDM 400 in Figure 22) to insert a test signal on the optical fiber (Daems: 22).
But, in Figure 2 of Daems, the wavelength dependent multiplexer (WDM 4) is on the leading fiber (22), not on the fibers (24) after the splitter 12.
However, Lam et al discloses an optical fiber monitoring apparatus (Figures 1-3 and 6), and the OTDR operates at a different wavelength (wavelength associated with OTDR 135) than a traffic wavelength (Lam: wavelengths associated with the OLT TX/RX 125; column 4 lines 50-56), and a wavelength dependent multiplexer (Lam: e.g., wavelength selective 3-port optical couplers 210) to insert a test signal on the optical fiber (145 in Figure 3; or 210 in Figures 2 and 6).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Lam et al to the system/method of Smith et al and Minami et al and Daems and Nakajima et al so that the test/monitoring signals and the data traffic can be properly sent to the desired destination without interference.
Claims 10-13 and 15 are rejected under 35 U.S.C. 103 as being unpatentable over Smith et al (US 2008/0031624) in view of Chen et al (US 9,435,712) and Minami et al (US 6,310,702) and Daems (US 2011/0268438) and Nakajima et al (US 2009/0190921).
1). With regard to claim 10, Smith et al discloses an optical fiber monitoring apparatus (Figure 1, the combination of OTDR 10, splitters 14/16 and fibers connecting the splitters etc.) comprising:
an OTDR (OTDR 10, [0007]-[0010], or the combination of OTDR and the splitter 14) including an OTDR optical source (the optical source that sends the light to the splitters/fibers; [0009], “light emitted by OTDR 10 travels through several spans of fiber as well as splitters 14 and 16”), wherein the OTDR is optically connected to N optical fibers (Figure 1, e.g., the splitter 16 is connected to 8 optical fibers, [0008]), wherein N is greater than one (e.g., N is 8); and
wherein the OTDR is a simultaneous multi-channel OTDR (Figure O1 above, which is adapted from Smith’s Figure 1, and the dotted box is added to show the structure corresponding to claimed “multi-channel OTDR”) having multiple, parallel inputs/outputs (e.g., the eight inputs/outputs associated with the splitter 14) each coupled through a dedicated optical fiber (one of the eight fibers, each between the splitter 14 and one splitter 16) to one of a plurality of 1 x N independent splitters (one of the eight 1x8 independent splitters 16);
an OTDR optical receiver (because it is an OTDR, it is inherent that a receiver is in the OTDR 135 so to detect the reflected signals, [0007]-[0009]); and
a 1 x N optical splitter (one of the 1 x 8 splitters 16), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (any one of the 1 x N optical splitter is one of the eight 1 x 8 optical splitters 16);
wherein N is greater than one (e.g., 1 x 8 splitter, [0008]),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (Figure 1, 1 x 8 splitter has 8 test port optical fiber outputs), and
wherein each test port optical fiber output is optically connectable to an optical fiber (Figure 1, fibers between splitter 16 and ONT 18) to optically connect the optical fiber to the OTDR optical source and the OTDR optical receiver (Figure 1, the optical fiber between splitter 16 and ONT 18 is connected to the OTDR via the splitters 14/16 and fiber between splitter 14 and splitter 16) for simultaneous monitoring of each test port optical fiber output by the OTDR ([0007]-[0009]).
But, in Figure 10, Smith et al does not expressly show the detail inside the OTDR, or Smith et al does not expressly disclose: an optical coupler optically inserted between the OTDR optical source and the OTDR optical receiver, and the 1 x N optical splitter; and Smith et al also does not expressly disclose each of the N optical fibers has dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers, and wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate to implement a plurality of splitting ratios.
Regarding the optical coupler and optical source and receiver etc., however, to implement a coupler in the OTDR so that one port is used to send a test signal out and receive reflected signal is well known in the art. E.g., Chen et al discloses an optical transmission system/method with OTDR, as shown in Figure 3, the OTDR includes an optical coupler (340) optically inserted between the OTDR optical source (310/320), the OTDR optical receiver (330), and an 1 x N optical splitter (120 in Figure 1).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use a coupler as taught by Chen et al to the OTDR of Smith et al so that the test signal can be conveniently sent to a splitter and reflected signals can be properly directed to a detector/receiver via a common port of the coupler.
Regarding dedicated reflectors connected to fiber ends, however, to implement dedicated reflectors at the ends of optical fibers are well known in the art so to get a baseline power levels or attenuations. E.g., Minami et al discloses a testing apparatus (Figure 1 etc.) for simultaneous monitoring of each test port optical fiber (C1, C2, D1, D2 and D3) by an OTDR (Figures 2 and 5 etc.). As shown in Figure 1 of Minami et al, each optical fiber has a dedicated reflector (EC1, EC2, ED1, ED2 and ED3); and “FIG. 2 is a graph showing a response waveform representing response light containing reflection beams and back scattering beams, which are measured by an OTDR measurement device shown in FIG. 1 before occurrence of fault” (column 3 lines 16-19); “a vertical axis of FIG. 2 represents a level of the response light which is a mixture of the reflection beams and back scattering beams given from the optical fibers A to D3 respectively. A spike wave emerges at each of points of the waveform of FIG. 2 which correspond to the terminal points EC1, EC2, ED1, ED2 and ED3 of the optical fibers C1, C2, D1, D2 and D3 respectively. This spike wave is produced based on Fresnel reflection. The terminal point EC1 is located optically in the closest proximity to the OTDR measurement device MS1. So, other terminal points are located with different distances from the OTDR measurement device MS1, wherein locations of them become farther from the device MS1 in an order of ED1, ED2, ED3 and EC2. That is, the terminal point EC2 is located at the farthest place from the device MS1” (column 4 lines 49-64); “With regard to record events that are recorded in connection with the measurement times lying between t1 and tk, there occurs no change in optical power, so it is possible to make a decision that an abnormal state does not exist. With regard to record events that are recorded in connection with the measurement times of tk and tk+1, a change occurs in optical power, so it is possible to make a decision that an abnormal state exists. Based on the time that the abnormal state occurs, it is possible to calculate a fault distance (or fault location) with ease”. That is, Fig. 2 is an initial measurement, and is a baseline to be compared when any other events occur. As shown in Figure 5, an event “ED2’ ” occurs. Figure O2 above shows the comparison between Minami’s Figure 2 and Figure 5.
As shown in Figure O2 above, “the location of the terminal point ED2 of the optical fiber D2 on the waveform (see FIG. 2), which is measured at the time tk, is shifted to a location of a terminal point ED2' on the waveform (see FIG. 5), which is measured at the time tk+1. So, it can be estimated that a fault occurs in an interval of time between tk and tk+1. In addition, a fault line on which the fault occurs matches with the optical fiber D2 whose terminal point is shifted as described above. Further, a fault distance matches with a shift distance by which the location of the terminal point ED2 at the time tk is shifted to the location of the terminal point ED2' at the time tk+1” (column 6 lines 19-44); Minami’s Figure 2 shows the measured power level (attenuation) of reflected signal vs fiber distance; the longer the fiber, the signal intensity is attenuated more; and when a fault occurs on fiber D2, the original signal ED2 is completed “attenuated” or disappeared, and a new signal at ED2’ comes; therefore, what are showed in Figure 2, which are measured “before occurrence of fault”, are calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers. Although Minami et al does not use the word “calibrated”, as discussed above, the processing to obtain the waveform shown in Figure 2 and the purpose/usage of Figure 2 are actually making the Figure 2 be “calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers”. Another prior art, Daems, also discloses a system/method for “ABSOLUTE OPTICAL ATTENUATION MEASUREMENT WITH OTDR” (title), and “Devices and methods for optical measurements in point-to-point and point-to-multipoint networks, e.g. like PON networks with splitters are described in which reflected power from some known reflections at the end of the lines is used to determine the attenuation and stability of the attenuation of each line” (Abstract). As shown in Figures 2 and 4 etc., reflectors (14 and 16 in Figure 2, or Ref R1 and Ref R2 in Figure 4; [0042]-[0045] and [0059] etc.) are implemented at the end of fibers, and “FIG. 4 shows how test equipment in accordance with the present invention can be calibrated” ([0029]) and “This calibration can be done when setting up the optical network. Once calibrated, the measurement of absolute loss can be done without further use of power meters” ([0059]); and “Accurate loss measurements are possible from just one side of the network through the splitter” ([0064]); and “It can be understood from the above that the measured absolute values of loss are obtained by methods and devices according to the present invention. As an extension of the present invention, the network can be monitored over time and changes in loss can be detected, e.g. as caused by a sharp bend introduced into a fiber. The measurement of absolute loss allows a change over time to be detected, whereas relative methods may suffer from changes in conditions between measurements which alter the result”; therefore, Daems teaches/suggests “dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”. In Figures 2 and 4, Daems uses the power level of the signal reflected from the retuning device 10 as a reference to calculate the “absolute loss” of each branch ([0049]-[0059]); and in Minami’s Figures 2 and 5, the power level of the signal reflected from the coupler CP1 is used as a reference to evaluate the signal levels/loss/attenuations of different fiber paths (Figure 2, at Distance 0 “CP1”, the power is normalized to “1”, or P/P0 is 1; and all other signal levels reflected from different paths/points are relative to or compared with the power level “1” reflected by CP1); then, the scheme or processes used for calculate a value representative of the absolute loss of each branch also can be applied to the system of combined Smith et al and Minami et al.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply dedicated reflectors at the ends of fibers as taught by Minami et al and Daems to the system/method of Smith et al and Chen et al so that a baseline or calibrated reference signal waveforms can be obtained, and fault events and position at faults can be accurately identified.
Regarding the splitters with a plurality of splitting ratios, first, for the embodiment of Figure 2 etc., Smith et al states “It will be apparent to those skilled in the art that various modifications and variations can be made to this invention without departing from the spirit or scope of the invention”; and Minami et al discloses a plurality of 1 x N optical splitters (Figure 1) with a plurality of splitting ratios (e.g., CP2 having 1:2 splitting ratio, and CP3 having a 1:3 splitting ratio). Second, Nakajima et al discloses an optical fiber monitoring system/method (Figures 1 and 22 etc.) comprising:
an OTDR (2 in Figure 1, [0170], “an OTDR (Optical Time Domain Reflectometer) is used as the test apparatus 2, and ONUs (Optical Network Units) are used as the terminators 4 is described”) including an OTDR optical source (the optical source that sends the light to the fiber f1/splitter 3a; [0010], “an OTDR test apparatus (including a light source) 1122 for utilizing backscattering light to measure a loss of the optical fiber and to detect a failure and a location of failure”), wherein the OTDR is optically connected to N optical fibers (f5-f6, or f7-f9), each having dedicated reflectors terminators 4a-4f etc. in Figures 1 and 5-7 etc., Abstract, and [0107]-[0113] etc.; e.g., fiber f5 has a reflector/terminator 4a, and fiber f6 has a reflector/terminator 4b. Figure 22, [0237], “the optical fiber lengths from the measurement apparatus 350 to the respective ONUs 420-1 to 420-N as the terminators are previously designed to be different when the optical fibers are deployed.”) connected to an end (Figures 1 and 5-7, terminator. Figure 22, the ONU) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (Abstract, and [0117]-[0122] etc., “In the normal information recording portion 14b, information with regard to intensities of the reflected lights which, after being emitted from the test apparatus 2 via the splitters 3, are reflected and returned by the respective terminators 4 is previously recorded. The intensities of the reflected lights recorded in this normal information recording portion 14b are those from the respective terminators 4 in the case where there is no failure in the optical lines f (f1 to f10)”, and “The attenuation amount determination portion 15 determines by how much the reflected light intensity of the predetermined terminator 4 previously recorded in the normal information recording portion 14b is attenuated from the corresponding reflected light intensity recorded in the monitored information recording portion 14c. Furthermore, the attenuation amount determination portion 15 determines whether or not the attenuated amount is equal in value to the attenuated amount of the other terminators 4 belonging to the same group”. And Figure 3, “one example of group information recorded in the group information recording portion 14a. As shown in the figure, information with regard to the terminators 4 connected to the same splitter 3 is recorded as group information, classified for every group. For example, the terminators 4a, 4b connected to the splitter 3b are recorded as in group g1”), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”), and
wherein the OTDR is a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a forms a multi-channel OTDR, which has three parallel inputs/outputs associated with fibers f2, f3 and f4) having multiple, parallel inputs/outputs (e.g., the three parallel inputs/outputs for the fibers f2-f4) each coupled through a dedicated optical fiber to one of a plurality of 1 x N independent splitters (3b-3d in Figure 1 etc.);
an OTDR optical receiver ([0109], “The test apparatus 2 emits an optical signal to the splitter 3a and receives an optical signal emitted by the splitter 3a via the optical line f1 based on the control by the optical line monitoring apparatus 1”, it is inherent that an OTDR optical receiver is in the test apparatus 2); and
wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., the splitter 3b), wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate ([0110], “As a splitter 3, for example a PLC (Planar Lightwave Circuit) type splitter can be used in which optical waveguides are branched in a tree-like manner on a silica substrate”, and [0184]) to implement a plurality of splitting ratios (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”);
wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (e.g., the splitter 3b has two test port optical fiber outputs), and
wherein each test port optical fiber output is optically connectable to an optical fiber (e.g., the two test ports of the splitter 3b is optically connectable to two optical fibers f5 and f6, respectively) to optically connect the optical fiber to the OTDR optical source and the OTDR optical receiver for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 1 and 5-7 etc. and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the splitter arrangement as taught by Nakajima et al to the system/method of Smith et al and Chen et al and Minami et al and Daems so that a compact, high reliable, excellent uniform (even power split), low wavelength dependent splitting assembly (having a plurality of splitters) can be obtained, and the splitting assembly is highly scalable to many channels.
2). With regard to claim 11, Smith et al and Chen et al and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claim 10 above. And the combination of Smith et al and Chen et al and Minami et al and Daems and Nakajima et al further discloses wherein the OTDR optical source includes a laser (e.g., laser 310 in Chen).
3). With regard to claim 12, Smith et al and Chen et al and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claim 10 above. And the combination of Smith et al and Chen et al and Minami et al and Daems and Nakajima et al further discloses wherein the OTDR optical receiver includes a photodiode (e.g., 330 in Chen).
4). With regard to claim 13, Smith et al and Chen et al and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claim 10 above. And the combination of Smith et al and Chen et al and Minami et al and Daems and Nakajima et al further discloses wherein the optical coupler is an M-port optical coupler (e.g., 3-port optical coupler 340 in Chen).
5). With regard to claim 15, Smith et al and Chen et al and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claims 10 and 13 above. And the combination of Smith et al and Chen et al and Minami et al and Daems and Nakajima et al further discloses wherein M is equal to three (Chen: 3-port coupler 340).
Claim 14 is rejected under 35 U.S.C. 103 as being unpatentable over Smith et al and Chen et al and Minami et al and Daems and Nakajima et al as applied to claims 10 and 13 above, and in further view of Husbands (US 4,449,043).
Smith et al and Chen et al and Minami et al and Daems and Nakajima et al discloses all of the subject matter as applied to claims 10 and 13 above. But, Smith et al and Chen et al and Minami et al and Daems and Nakajima et al do not expressly disclose wherein the optical coupler includes an additional output connected to an additional measurement port.
However, to add additional port to a coupler for additional purpose is known in the art. E.g., Husbands discloses a system/method to monitor fiber connections etc. As shown in Figure 1, instead of a 3-port coupler, a 4-port coupler is used: port 28 for light source, port 30 for receiving reflected signals, port 34 for transmission/receiving (common port), an additional output (B) connected to an additional measurement port (32, for monitoring the output signals).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Husbands to the system/method of Smith et al and Chen et al and Minami et al and Daems and Nakajima et al so that additional port can be used for additional/auxiliary purpose to enhance the function of the system/method.
Claims 24-25 are rejected under 35 U.S.C. 103 as being unpatentable over Smith et al and Minami et al and Daems and Nakajima et al as applied to claims 1 and 16 above, and in further view of Chen et al (US 9,435,712).
Smith et al and Minami et al and Daems and Nakajima et al disclose all of the subject matter as applied to claims 1 and 16 above. And the combination of Smith et al and Minami et al and Daems and Nakajima et al further discloses the optical fiber monitoring apparatus according to claims 1 and 16, further comprising a receiver (because it is an OTDR, it is inherent that a receiver is in the OTDR so to detect the reflected signals. Nakajima: [0109], “The test apparatus 2 emits an optical signal to the splitter 3a and receives an optical signal emitted by the splitter 3a via the optical line f1 based on the control by the optical line monitoring apparatus 1”, it is inherent that an OTDR optical receiver is in the test apparatus 2).
But, Smith et al and Minami et al and Daems and Nakajima et al do not expressly show the detail inside the OTDR, or Smith et al and Minami et al and Daems and Nakajima et al do not expressly show a photodiode is in the receiver.
However, Chen et al discloses an optical transmission system/method with OTDR, as shown in Figure 3, the OTDR includes an optical coupler (340) optically inserted between the OTDR optical source (310/320), the OTDR optical receiver (330), and an 1 x N optical splitter (120 in Figure 1). And the OTDR optical receiver includes a photodiode (e.g., 330).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Chen et al to the OTDR of Smith et al and Minami et al and Daems and Nakajima et al so that the reflected test/monitoring signal can be properly detected.
Claims 1-3, 9, 16-18 and 22-23 are rejected under 35 U.S.C. 103 as being unpatentable over Lam et al (US 9,240,855) in view of Minami et al (US 6,310,702) and Nakajima et al (US 2009/0190921) and Daems (US 2011/0268438).
1). With regard to claim 1, Lam et al discloses an optical fiber monitoring apparatus (Figures 1-3 and 6) comprising:
an optical time domain reflectometer (OTDR) (OTDR 135 in Figure 3, or the combination of OTDR 135 and the switch 215), wherein the OTDR is optically connected to N optical fibers (fibers 145), each having dedicated reflectors (demarcation devices 150 as shown in Figure 1; “demarcation devices 150 each include a wavelength selective reflector that is reflective to the optical test signal output by OTDR unit 135 (e.g., in the 1625-1670 nm optical band) while transmissive to the upstream and downstream data signals communicated between OLT 125 and ONUs 115 (e.g., 1310 nm upstream and 1490 nm downstream)”, column 4 lines 43-56) connected to an end (Figure 1, column 4 lines 43-56) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (column 7 line 33-52, and steps 425-440, “In a process block 435, the reflection signature is analyzed to determine if a fiber fault exists, and if so, where the fiber fault is located. In one embodiment, the reflection signature is analyzed by comparing it to a reference reflection signature stored for the given test PON (i.e., selected optical splitter 310). FIG. 5B illustrates an example reference signature 510. A reference test signature is stored for each optical splitter 310. The reference signature may be obtained during testing conducted after the initial fiber plant and during subsequent service intervals when new ONUs 115 are added to a given subset. The reference test signatures characterize each subset of pt-2-pt fiber links 145 as a unique test PON. If a new reflection peak is present in the newly acquired reflection signature 505 and an existing peak in the reference reflection signature 510 is either gone or smaller, then a fiber fault can be assumed to be present in the associated fiber link 145. If the newly acquired reflection signature 505 is identical to the stored reference reflection signature 510, then it can be assumed that the loss of service is due to an error in the CPE and not in the fiber plant”. As shown in Figure 5A, when compared with Figure 5B, an “original signature peak disappears due to fiber break” at the location/distance shown in vertical dotted line, and a new peak is present at “Reflection Due to fiber fault”; and step 435 in Figure 4 is “Analyze Reflection Signature (E.G., Compare to Reference Signature)”; that is, Figure 5B is a reference signature (510), or is a type of calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers), wherein N is greater than one (Figures 2-3 and 6, more than one fibers connected to each splitter); and
a 1 x N optical splitter (e.g., optical splitter 310 in Figures 3 and 6) that is optically connected to the OTDR,
wherein N is greater than one (1:M, M is greater than 1),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (M outputs. Column 6 lines 10-43), and
wherein the OTDR is a multi-channel OTDR (Figure 3, the switch has N outputs, which correspond to N channels) having multiple, parallel inputs/outputs (1:N switch, N parallel inputs/outputs) each coupled through a dedicated optical fiber (fiber between the switch 215 and a splitter 310) to one of a plurality of 1 x N an independent splitters (e.g., one of the N splitters 310), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., any one of the 1:M optical splitter is one of the N 1:M optical splitters 310), and further wherein each test port optical fiber output (each of the outputs from the splitter 310 is connected to a fiber 145 respectively; or Figure 6, “TO FIBER LINKS”) is optically connectable to an optical fiber (one of the fibers 145) to optically connect the optical fiber to the OTDR for simultaneous monitoring of a group of test ports optical fibers (e.g., the group of fibers connected to the splitter at the left side of Figure 3), which is determined by the switch 310, output by the OTDR.
But, Lam et al does not expressly disclose wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate to implement a plurality of splitting ratios, wherein the OTDR is a simultaneous multi-channel OTDR, wherein each test port optical fiber output is optically connectable to an optical fiber to optically connect the optical fiber to the OTDR for simultaneous monitoring of each test port optical fiber output by the OTDR; and Lam et al also does not expressly use the phrase “calibrated” to describe the Figure 5B.
In Figure 3 or Figure 6 of Lam et al, a single OTDR and one switch are used, and because of the switch, at one time only one specific splitter is connected to the OTDR or only one group of fibers are connected to the OTDR, and other groups of fibers (connected to other splitters) cannot be simultaneously monitored since the single OTDR can only be connected to one group of fibers at one time. E.g., in Figure 3, while the switch (215) is connected to the left side splitter (310), the splitter 310 is connected to multiple (M) fibers, and all the fibers 1-M are monitored simultaneously by the OTDR; and when the switch (215) is connected to the right side splitter (310), the splitter 310 is connected to multiple (M) fibers (e.g., another group of fibers), and all the fibers corresponding to right side splitter are monitored simultaneously by the OTDR.
However, to use a splitter, instead of a switch, to monitor a large number of fiber links simultaneously by a single OTDR are known in the art. E.g., Minami et al discloses a testing apparatus (Figure 1 etc.) for simultaneous monitoring of each test port optical fiber (C1, C2, D1, D2 and D3) output by the OTDR (Figures 2 and 5 etc.).
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Figure O3
As shown in Figure 1 of Minami et al, or Figure O3 above, which is adapted from Minami’s Figure 1 and the dotted box is added to show the structure corresponding to claimed “multi-channel OTDR”, the multi-channel OTDR is a simultaneous multi-channel OTDR having multiple, parallel inputs/outputs (e.g., the outputs of the coupler CP1, which is a “branch” device, or a splitter, “the optical fiber CP1 wherein it is subjected to branching into two directions”, column 3 line 46 to column 4 line 19) each coupled through a dedicated optical fiber (B1 and B2) to one of a plurality of independent splitters (CP2 and CP3), wherein the plurality of independent splitters (CP2 and CP3) includes the 1x2 splitter (CP2), and further wherein each test port optical fiber output is optically connectable to an optical fiber (C1, C2, D1, D2, or D3) to optically connect the optical fiber to the OTDR for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 2-6). In Figure 1 of Minami et al, the independent splitters CP2 and CP3 may have different splitting ratio: e.g., CP2 is 1:2, and CP is 1:3.
Another prior art, Nakajima et al, discloses an optical fiber monitoring system/method (Figures 1 and 22 etc.) comprising:
an optical time domain reflectometer (OTDR) (2 in Figure 1, [0170], “an OTDR (Optical Time Domain Reflectometer) is used as the test apparatus 2, and ONUs (Optical Network Units) are used as the terminators 4 is described”), wherein the OTDR is optically connected to N optical fibers (f5/f6, or f7-f9), each having dedicated reflectors (terminators 4a-4f etc. in Figures 1 and 5-7 etc., Abstract, and [0107]-[0113] etc.; e.g., fiber f5 has a reflector/terminator 4a, and fiber f6 has a reflector/terminator 4b. Figure 22, [0237], “the optical fiber lengths from the measurement apparatus 350 to the respective ONUs 420-1 to 420-N as the terminators are previously designed to be different when the optical fibers are deployed.”) connected to an end (Figures 1 and 5-7, terminator. Figure 22, the ONU) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (Abstract, and [0117]-[0122] etc., “In the normal information recording portion 14b, information with regard to intensities of the reflected lights which, after being emitted from the test apparatus 2 via the splitters 3, are reflected and returned by the respective terminators 4 is previously recorded. The intensities of the reflected lights recorded in this normal information recording portion 14b are those from the respective terminators 4 in the case where there is no failure in the optical lines f (f1 to f10)”, and “The attenuation amount determination portion 15 determines by how much the reflected light intensity of the predetermined terminator 4 previously recorded in the normal information recording portion 14b is attenuated from the corresponding reflected light intensity recorded in the monitored information recording portion 14c. Furthermore, the attenuation amount determination portion 15 determines whether or not the attenuated amount is equal in value to the attenuated amount of the other terminators 4 belonging to the same group”. And Figure 3, “one example of group information recorded in the group information recording portion 14a. As shown in the figure, information with regard to the terminators 4 connected to the same splitter 3 is recorded as group information, classified for every group. For example, the terminators 4a, 4b connected to the splitter 3b are recorded as in group g1”), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”); and
a 1 x N optical splitter (e.g., the splitter 3b in Figure 1, or 410 in Figure 22) that is optically connected to the OTDR (Figures 1 and 22 etc.), wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate ([0110], “As a splitter 3, for example a PLC (Planar Lightwave Circuit) type splitter can be used in which optical waveguides are branched in a tree-like manner on a silica substrate”, and [0184]) to implement a plurality of splitting ratios (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (e.g., the splitter 3b has two test port optical fiber outputs), and
wherein the OTDR is a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a forms a multi-channel OTDR, which has three parallel inputs/outputs associated with fibers f2, f3 and f4), having multiple parallel inputs/outputs (e.g., the three parallel inputs/outputs for the fibers f2-f4) each coupled through a dedicated optical fiber (one of the f2, f3, or f4) to one of a plurality of 1 x N independent splitters (3b-3d in Figure 1 etc.), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., the splitter 3b), and further wherein each test port optical fiber output is optically connectable to an optical fiber (e.g., the two test ports of the splitter 3b is optically connectable to two optical fibers f5 and f6, respectively) to optically connect the optical fiber to the OTDR for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 1 and 5-7 etc. and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”).
That is, Nakajima et al discloses a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a, which has three parallel inputs/outputs associated with fibers f2, f3 and f4) has three parallel inputs/outputs each coupled through a dedicated optical fiber (f2, or f3, or f4) to one of a plurality of 1 x N independent splitters (3b-3d); and the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate to implement a plurality of splitting ratios ([0184], and Figure 1 etc.).
As disclosed by Minami et al and Nakajima et al, by using one more splitter (Minami: CP1; or Nakajima: 3a), which is connected to another stage of splitters (Minami: CP2 and CP3; or Nakajima: 3b-3d), the OTDR can monitor a large number of fibers simultaneously, and all the fibers connected to the splitters are simultaneous monitored. That is, the combination of Lam et al and Minami et al and Nakajima et al teaches/suggests wherein the OTDR is a simultaneous multi-channel OTDR having multiple, parallel inputs/outputs each coupled through a dedicated optical fiber to an independent splitter, and further wherein each test port optical fiber output is optically connectable to an optical fiber to optically connect the optical fiber to the OTDR for simultaneous monitoring of each test port optical fiber output by the OTDR. Following Figure O4 is a diagram showing the combination of Lam et al and Minami et al and Nakajima et al.
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Figure O4
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Minami et al and Nakajima et al to the system/method of Lam et al so that all the fibers (channels) can be monitored at the same time, and the system capacity is increased, and the functions of the monitoring system is enhanced; and by implementing the splitters having a plurality of splitting ratio implemented on a PLC, a compact, high reliable, excellent uniform (even power split), low wavelength dependent splitting assembly (having a plurality of splitters) can be obtained, and the splitting assembly is highly scalable to many channels.
Regarding the calibrated reflective signals, as discussed above, the reference reflection signature 510 shown in Figure 5B is a type of “calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers” because the reflection signature 510 is “obtained during testing conducted after the initial fiber plant and during subsequent service intervals when new ONUs 115 are added to a given subset” and for comparison determining an attenuation (disappearance) and fault for each of the N optical fibers. Also, for the testing apparatus shown in Figure 1 etc., Minami et al discloses that each optical fiber has a dedicated reflector (EC1, EC2, ED1, ED2 and ED3); and “FIG. 2 is a graph showing a response waveform representing response light containing reflection beams and back scattering beams, which are measured by an OTDR measurement device shown in FIG. 1 before occurrence of fault” (column 3 lines 16-19); “a vertical axis of FIG. 2 represents a level of the response light which is a mixture of the reflection beams and back scattering beams given from the optical fibers A to D3 respectively. A spike wave emerges at each of points of the waveform of FIG. 2 which correspond to the terminal points EC1, EC2, ED1, ED2 and ED3 of the optical fibers C1, C2, D1, D2 and D3 respectively. This spike wave is produced based on Fresnel reflection. The terminal point EC1 is located optically in the closest proximity to the OTDR measurement device MS1. So, other terminal points are located with different distances from the OTDR measurement device MS1, wherein locations of them become farther from the device MS1 in an order of ED1, ED2, ED3 and EC2. That is, the terminal point EC2 is located at the farthest place from the device MS1” (column 4 lines 49-64); “With regard to record events that are recorded in connection with the measurement times lying between t1 and tk, there occurs no change in optical power, so it is possible to make a decision that an abnormal state does not exist. With regard to record events that are recorded in connection with the measurement times of tk and tk+1, a change occurs in optical power, so it is possible to make a decision that an abnormal state exists. Based on the time that the abnormal state occurs, it is possible to calculate a fault distance (or fault location) with ease”. That is, Fig. 2 is an initial measurement, and is a baseline to be compared when any other events occur. As shown in Figure 5, an event “ED2’ ” occurs. And Nakajima also teaches to compare reflected signals with the recorded normal information so to determine whether an abnormal state exists (Figures 4, 11-12 and 16 etc.).
As shown in Figure O2 above, “the location of the terminal point ED2 of the optical fiber D2 on the waveform (see FIG. 2), which is measured at the time tk, is shifted to a location of a terminal point ED2' on the waveform (see FIG. 5), which is measured at the time tk+1. So, it can be estimated that a fault occurs in an interval of time between tk and tk+1. In addition, a fault line on which the fault occurs matches with the optical fiber D2 whose terminal point is shifted as described above. Further, a fault distance matches with a shift distance by which the location of the terminal point ED2 at the time tk is shifted to the location of the terminal point ED2' at the time tk+1” (column 6 lines 19-44); Minami’s Figure 2 shows the measured power level (attenuation) of reflected signal vs fiber distance; the longer the fiber, the signal intensity is attenuated more; and when a fault occurs on fiber D2, the original signal ED2 is completed “attenuated” or disappeared, and a new signal at ED2’ comes; therefore, what are showed in Figure 2, which are measured “before occurrence of fault”, are calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers. Then, although Minami et al does not use the word “calibrated”, as discussed above, the processing to obtain the waveform shown in Figure 2 and the purpose/usage of Figure 2 are actually making the Figure 2 be “calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers”. Another prior art, Daems, also discloses a system/method for “ABSOLUTE OPTICAL ATTENUATION MEASUREMENT WITH OTDR” (title), and “Devices and methods for optical measurements in point-to-point and point-to-multipoint networks, e.g. like PON networks with splitters are described in which reflected power from some known reflections at the end of the lines is used to determine the attenuation and stability of the attenuation of each line” (Abstract). As shown in Figures 2 and 4 etc., reflectors (14 and 16 in Figure 2, or Ref R1 and Ref R2 in Figure 4; [0042]-[0045] and [0059] etc.) are implemented at the end of fibers, and “FIG. 4 shows how test equipment in accordance with the present invention can be calibrated” ([0029]) and “This calibration can be done when setting up the optical network. Once calibrated, the measurement of absolute loss can be done without further use of power meters” ([0059]); and “Accurate loss measurements are possible from just one side of the network through the splitter” ([0064]); and “It can be understood from the above that the measured absolute values of loss are obtained by methods and devices according to the present invention. As an extension of the present invention, the network can be monitored over time and changes in loss can be detected, e.g. as caused by a sharp bend introduced into a fiber. The measurement of absolute loss allows a change over time to be detected, whereas relative methods may suffer from changes in conditions between measurements which alter the result”; therefore, Daems teaches/suggests “dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”. In Figures 2 and 4, Daems uses the power level of the signal reflected from the retuning device 10 as a reference to calculate the “absolute loss” of each branch ([0049]-[0059]); and in Minami’s Figures 2 and 5, the power level of the signal reflected from the coupler CP1 is used as a reference to evaluate the signal levels/loss/attenuations of different fiber paths (Figure 2, at Distance 0 “CP1”, the power is normalized to “1”, or P/P0 is 1; and all other signal levels reflected from different paths/points are relative to or compared with the power level “1” reflected by CP1); then, the scheme or processes used for calculate a value representative of the absolute loss of each branch also can be applied to the system of combined Lam et al and Minami et al and Nakajima et al.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Daems to the system/method of Lam et al and Minami et al and Nakajima et al so that accurate calibrated reflective signals for use as a reference for determining an attenuation for each optical fiber can be obtained, and fault events and position at faults can be accurately identified.
2). With regard to claim 2, Lam et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 1 above. And the combination of Lam et al and Minami et al and Nakajima et al and Daems further discloses wherein the OTDR is optically connected to N optical fibers including the optical fiber to extract, from each optical fiber of the N optical fibers, information by analyzing signals returned from the N optical fibers to the N test port optical fiber outputs (Lam: Abstract, and column 3 line 61 to column 4 line 17; Figure 4, step 435, column 7 line 33-39. Minami: Figures 2-6 etc. Nakajima: Figures 4, 11-12 and 16 etc.).
3). With regard to claim 3, Lam et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 1 above. And the combination of Lam et al and Minami et al and Nakajima et al and Daems further discloses wherein the OTDR is optically connected to N optical fibers including the optical fiber to compare, for the N optical fibers, N simultaneous test results to a reference test result to identify changes on at least one optical fiber under test of the N optical fibers (Lam: column 7 line 33-52, “A reference test signature is stored for each optical splitter 310. The reference signature may be obtained during testing conducted after the initial fiber plant and during subsequent service intervals when new ONUs 115 are added to a given subset. The reference test signatures characterize each subset of pt-2-pt fiber links 145 as a unique test PON. If a new reflection peak is present in the newly acquired reflection signature 505 and an existing peak in the reference reflection signature 510 is either gone or smaller, then a fiber fault can be assumed to be present in the associated fiber link 145. If the newly acquired reflection signature 505 is identical to the stored reference reflection signature 510, then it can be assumed that the loss of service is due to an error in the CPE and not in the fiber plant.” Minami: Minami: as discussed in claim 1 rejection, Figure 2 is a reference test result waveform or baseline, and Figure 5 shows ED2’ peak, which is due to “ED2 … is shifted to a location of a terminal point ED2' on the waveform”, and “a fault distance matches with a shift distance by which the location of the terminal point ED2 at the time tk is shifted to the location of the terminal point ED2' at the time tk+1” column 6 lines 18-44; “the fault determination is made by comparing results of the separative analysis, which are obtained at the measuring times respectively. By the fault determination, it is possible to determine a fault line and a fault location (or fault distance) as well as a fault time” column 2 line 64 to column 3 line 3. Nakajima: Figures 1, 4-7, 11-12 and 16 etc.).
4). With regard to claim 9, Lam et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 1 above. And the combination of Lam et al and Minami et al and Nakajima et al and Daems further discloses wherein the OTDR operates at a different wavelength (Lam: wavelength associated with OTDR 135) than a traffic wavelength (Lam: wavelengths associated with the OLT TX/RX 125), further comprising:
a wavelength dependent multiplexer (Lam: e.g., wavelength selective 3-port optical couplers 210) to insert a test signal on the optical fiber (also refer Figure 22 of Nakajima).
5). With regard to claim 16, Lam et al discloses an optical fiber monitoring apparatus (Figures 1-3 and 6) comprising:
an optical time domain reflectometer (OTDR) (OTDR 135 in Figures 1-3, or the combination of OTDR 135 and the switch 215), wherein the OTDR is optically connected to N optical fibers (fibers 145), each having dedicated reflectors (demarcation devices 150 as shown in Figure 1; “demarcation devices 150 each include a wavelength selective reflector that is reflective to the optical test signal output by OTDR unit 135 (e.g., in the 1625-1670 nm optical band) while transmissive to the upstream and downstream data signals communicated between OLT 125 and ONUs 115 (e.g., 1310 nm upstream and 1490 nm downstream)”, column 4 lines 43-56) connected to an end (Figure 1, column 4 lines 43-56) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (column 7 line 33-52, and steps 425-440, “In a process block 435, the reflection signature is analyzed to determine if a fiber fault exists, and if so, where the fiber fault is located. In one embodiment, the reflection signature is analyzed by comparing it to a reference reflection signature stored for the given test PON (i.e., selected optical splitter 310). FIG. 5B illustrates an example reference signature 510. A reference test signature is stored for each optical splitter 310. The reference signature may be obtained during testing conducted after the initial fiber plant and during subsequent service intervals when new ONUs 115 are added to a given subset. The reference test signatures characterize each subset of pt-2-pt fiber links 145 as a unique test PON. If a new reflection peak is present in the newly acquired reflection signature 505 and an existing peak in the reference reflection signature 510 is either gone or smaller, then a fiber fault can be assumed to be present in the associated fiber link 145. If the newly acquired reflection signature 505 is identical to the stored reference reflection signature 510, then it can be assumed that the loss of service is due to an error in the CPE and not in the fiber plant”. As shown in Figure 5A, when compared with Figure 5B, an “original signature peak disappears due to fiber break” at the location/distance shown in vertical dotted line, and a new peak is present at “Reflection Due to fiber fault”; and step 435 in Figure 4 is “Analyze Reflection Signature (E.G., Compare to Reference Signature)”; that is, Figure 5B is a reference signature (510), or is a type of calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers), wherein N is greater than one (Figures 2-3 and 6, more than one fibers connected to each splitter), wherein the OTDR is a multi-channel OTDR (Figure 3, the switch has N outputs, which correspond to N channels) having multiple, parallel inputs/outputs (1:N switch, N parallel inputs/outputs) each coupled through a dedicated optical fiber (fiber between the switch 215 and a splitter 310) to one of a plurality of 1 x N an independent splitters (e.g., one of the N splitters 310); and
a 1 x N optical splitter (e.g., optical splitter 310 in Figure 3 or Figure 6) that is optically connected to the OTDR to test at least one optical fiber of N optical fibers (Figure 3, fibers 145) that are optically connected to the 1 x N optical splitter (Figure 3, each output from the splitter is connected to a fiber 145, respectively), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., any one of the 1:M optical splitter is one of the N 1:M optical splitters 310),
wherein the 1 x N optical splitter (e.g., the splitter at the left side of Figure 3) includes N test port optical fiber outputs (M outputs; each output is connected to one fiber 145 via the coupler 210. Column 6 lines 10-43) for simultaneous monitoring of each test port optical fiber output by the OTDR (all the fibers connected to the splitter 310 at the left side are monitored simultaneously. Column 6 lines 10-43).
wherein N is greater than one (M is larger than one).
But, Lam et al does not expressly disclose wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate to implement a plurality of splitting ratios, wherein the OTDR is a simultaneous multi-channel OTDR having multiple, parallel inputs/outputs each coupled through a dedicated optical fiber to an independent splitter, and all the fibers connected to the independent splitters are monitored simultaneously; and Lam et al also does not expressly use the phrase “calibrated” to describe the Figure 5B.
In Figure 3 or Figure 6 of Lam et al, a single OTDR and one switch are used, and because of the switch, at one time only one specific splitter is connected to the OTDR or only one group of fibers are connected to the OTDR, and other groups of fibers (connected to other splitters) cannot be simultaneously monitored since the single OTDR can only be connected to one group of fibers at one time. E.g., in Figure 3, while the switch (215) is connected to the left side splitter (310), the splitter 310 is connected to multiple (M) fibers, and all the fibers 1-M are monitored simultaneously by the OTDR; and when the switch (215) is connected to the right side splitter (310), the splitter 310 is connected to multiple (M) fibers (e.g., another group of fibers), and all the fibers corresponding to right side splitter are monitored simultaneously by the OTDR.
However, to use a splitter, instead of a switch, to monitor a large number of fiber links simultaneously by a single OTDR are known in the art. E.g., Minami et al discloses a testing apparatus (Figure 1 etc.) for simultaneous monitoring of each test port optical fiber (C1, C2, D1, D2 and D3) output by the OTDR (Figures 2 and 5 etc.).
As shown in Figure 1 of Minami et al, or Figure O3 above, which is adapted from Minami’s Figure 1 and the dotted box is added to show the structure corresponding to claimed “multi-channel OTDR”, the multi-channel OTDR is a simultaneous multi-channel OTDR having multiple, parallel inputs/outputs (e.g., the outputs of the coupler CP1, which is a “branch” device, or a splitter, “the optical fiber CP1 wherein it is subjected to branching into two directions”, column 3 line 46 to column 4 line 19) each coupled through a dedicated optical fiber (B1 and B2) to one of a plurality of independent splitters (CP2 and CP3), wherein the plurality of independent splitters (CP2 and CP3) includes the 1x2 splitter (CP2), and further wherein each test port optical fiber output is optically connectable to an optical fiber (C1, C2, D1, D2, or D3) to optically connect the optical fiber to the OTDR for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 2-6). In Figure 1 of Minami et al, the independent splitters CP2 and CP3 may have different splitting ratio: e.g., CP2 is 1:2, and CP is 1:3.
Another prior art, Nakajima et al, discloses an optical fiber monitoring system/method (Figures 1 and 22 etc.) comprising:
an optical time domain reflectometer (OTDR) (2 in Figure 1, [0170], “an OTDR (Optical Time Domain Reflectometer) is used as the test apparatus 2, and ONUs (Optical Network Units) are used as the terminators 4 is described”), wherein the OTDR is optically connected to N optical fibers (f5/f6, or f7-f9), each having dedicated reflectors (terminators 4a-4f etc. in Figures 1 and 5-7 etc., Abstract, and [0107]-[0113] etc.; e.g., fiber f5 has a reflector/terminator 4a, and fiber f6 has a reflector/terminator 4b. Figure 22, [0237], “the optical fiber lengths from the measurement apparatus 350 to the respective ONUs 420-1 to 420-N as the terminators are previously designed to be different when the optical fibers are deployed.”) connected to an end (Figures 1 and 5-7, terminator. Figure 22, the ONU) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (Abstract, and [0117]-[0122] etc., “In the normal information recording portion 14b, information with regard to intensities of the reflected lights which, after being emitted from the test apparatus 2 via the splitters 3, are reflected and returned by the respective terminators 4 is previously recorded. The intensities of the reflected lights recorded in this normal information recording portion 14b are those from the respective terminators 4 in the case where there is no failure in the optical lines f (f1 to f10)”, and “The attenuation amount determination portion 15 determines by how much the reflected light intensity of the predetermined terminator 4 previously recorded in the normal information recording portion 14b is attenuated from the corresponding reflected light intensity recorded in the monitored information recording portion 14c. Furthermore, the attenuation amount determination portion 15 determines whether or not the attenuated amount is equal in value to the attenuated amount of the other terminators 4 belonging to the same group”. And Figure 3, “one example of group information recorded in the group information recording portion 14a. As shown in the figure, information with regard to the terminators 4 connected to the same splitter 3 is recorded as group information, classified for every group. For example, the terminators 4a, 4b connected to the splitter 3b are recorded as in group g1”), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”), wherein the OTDR is a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a forms a multi-channel OTDR, which has three parallel inputs/outputs associated with fibers f2, f3 and f4), having multiple parallel inputs/outputs (e.g., the three parallel inputs/outputs for the fibers f2-f4) each coupled through a dedicated optical fiber (one of the f2, f3, or f4) to one of a plurality of 1 x N independent splitters (splitters 3b-3d in Figure 1 etc.),
a 1 x N optical splitter (e.g., the splitter 3b in Figure 1, or 410 in Figure 22) that is optically connected to the OTDR (Figures 1 and 22 etc.) to test at least one optical fiber of N optical fibers that are optically connected to the 1x N optical splitter (Figures 4, 11-12 and 16 etc.; and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., the splitter 3b), wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate ([0110], “As a splitter 3, for example a PLC (Planar Lightwave Circuit) type splitter can be used in which optical waveguides are branched in a tree-like manner on a silica substrate”, and [0184]) to implement a plurality of splitting ratios (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (e.g., the splitter 3b has two test port optical fiber outputs) for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 1 and 5-7 etc. and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”),
wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”).
That is, Nakajima et al discloses a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a, which has three parallel inputs/outputs associated with fibers f2, f3 and f4) has three parallel inputs/outputs each coupled through a dedicated optical fiber (f2, or f3, or f4) to one of a plurality of 1 x N independent splitters (3b-3d); and the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate to implement a plurality of splitting ratios ([0184], and Figure 1 etc.).
As disclosed by Minami et al and Nakajima et al, by using one more splitter (Minami: CP1; or Nakajima: 3a), which is connected to another stage of splitters (Minami: CP2 and CP3; or Nakajima: 3b-3d), the OTDR can monitor a large number of fibers simultaneously, and all the fibers connected to the splitters are simultaneous monitored. That is, the combination of Lam et al and Minami et al and Nakajima et al teaches/suggests wherein the OTDR is a simultaneous multi-channel OTDR having multiple, parallel inputs/outputs each coupled through a dedicated optical fiber to an independent splitter, and further wherein each test port optical fiber output is optically connectable to an optical fiber to optically connect the optical fiber to the OTDR for simultaneous monitoring of each test port optical fiber output by the OTDR. Figure O4 above is a diagram showing the combination of Lam et al and Minami et al and Nakajima et al.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Minami et al and Nakajima et al to the system/method of Lam et al so that all the fibers (channels) can be monitored at the same time, and the system capacity is increased, and the functions of the monitoring system is enhanced; and by implementing the splitters having a plurality of splitting ratio implemented on a PLC, a compact, high reliable, excellent uniform (even power split), low wavelength dependent splitting assembly (having a plurality of splitters) can be obtained, and the splitting assembly is highly scalable to many channels.
Regarding the calibrated reflective signals, as discussed above, the reference reflection signature 510 shown in Figure 5B is a type of “calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers” because the reflection signature 510 is “obtained during testing conducted after the initial fiber plant and during subsequent service intervals when new ONUs 115 are added to a given subset” and for comparison determining an attenuation (disappearance) and fault for each of the N optical fibers. Also, for the testing apparatus shown in Figure 1 etc., Minami et al discloses that each optical fiber has a dedicated reflector (EC1, EC2, ED1, ED2 and ED3); and “FIG. 2 is a graph showing a response waveform representing response light containing reflection beams and back scattering beams, which are measured by an OTDR measurement device shown in FIG. 1 before occurrence of fault” (column 3 lines 16-19); “a vertical axis of FIG. 2 represents a level of the response light which is a mixture of the reflection beams and back scattering beams given from the optical fibers A to D3 respectively. A spike wave emerges at each of points of the waveform of FIG. 2 which correspond to the terminal points EC1, EC2, ED1, ED2 and ED3 of the optical fibers C1, C2, D1, D2 and D3 respectively. This spike wave is produced based on Fresnel reflection. The terminal point EC1 is located optically in the closest proximity to the OTDR measurement device MS1. So, other terminal points are located with different distances from the OTDR measurement device MS1, wherein locations of them become farther from the device MS1 in an order of ED1, ED2, ED3 and EC2. That is, the terminal point EC2 is located at the farthest place from the device MS1” (column 4 lines 49-64); “With regard to record events that are recorded in connection with the measurement times lying between t1 and tk, there occurs no change in optical power, so it is possible to make a decision that an abnormal state does not exist. With regard to record events that are recorded in connection with the measurement times of tk and tk+1, a change occurs in optical power, so it is possible to make a decision that an abnormal state exists. Based on the time that the abnormal state occurs, it is possible to calculate a fault distance (or fault location) with ease”. That is, Fig. 2 is an initial measurement, and is a baseline to be compared when any other events occur. As shown in Figure 5, an event “ED2’ ” occurs. And Nakajima also teaches to compare reflected signals with the recorded normal information so to determine whether an abnormal state exists (Figures 4, 11-12 and 16 etc.).
As shown in Figure O2 above, “the location of the terminal point ED2 of the optical fiber D2 on the waveform (see FIG. 2), which is measured at the time tk, is shifted to a location of a terminal point ED2' on the waveform (see FIG. 5), which is measured at the time tk+1. So, it can be estimated that a fault occurs in an interval of time between tk and tk+1. In addition, a fault line on which the fault occurs matches with the optical fiber D2 whose terminal point is shifted as described above. Further, a fault distance matches with a shift distance by which the location of the terminal point ED2 at the time tk is shifted to the location of the terminal point ED2' at the time tk+1” (column 6 lines 19-44); Minami’s Figure 2 shows the measured power level (attenuation) of reflected signal vs fiber distance; the longer the fiber, the signal intensity is attenuated more; and when a fault occurs on fiber D2, the original signal ED2 is completed “attenuated” or disappeared, and a new signal at ED2’ comes; therefore, what are showed in Figure 2, which are measured “before occurrence of fault”, are calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers. Then, the processing to obtain the waveform shown in Figure 2 and the purpose/usage of Figure 2 are actually making the Figure 2 be “calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers”. Another prior art, Daems, also discloses a system/method for “ABSOLUTE OPTICAL ATTENUATION MEASUREMENT WITH OTDR” (title), and “Devices and methods for optical measurements in point-to-point and point-to-multipoint networks, e.g. like PON networks with splitters are described in which reflected power from some known reflections at the end of the lines is used to determine the attenuation and stability of the attenuation of each line” (Abstract). As shown in Figures 2 and 4 etc., reflectors (14 and 16 in Figure 2, or Ref R1 and Ref R2 in Figure 4; [0042]-[0045] and [0059] etc.) are implemented at the end of fibers, and “FIG. 4 shows how test equipment in accordance with the present invention can be calibrated” ([0029]) and “This calibration can be done when setting up the optical network. Once calibrated, the measurement of absolute loss can be done without further use of power meters” ([0059]); and “Accurate loss measurements are possible from just one side of the network through the splitter” ([0064]); and “It can be understood from the above that the measured absolute values of loss are obtained by methods and devices according to the present invention. As an extension of the present invention, the network can be monitored over time and changes in loss can be detected, e.g. as caused by a sharp bend introduced into a fiber. The measurement of absolute loss allows a change over time to be detected, whereas relative methods may suffer from changes in conditions between measurements which alter the result”; therefore, Daems teaches/suggests “dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”. In Figures 2 and 4, Daems uses the power level of the signal reflected from the retuning device 10 as a reference to calculate the “absolute loss” of each branch ([0049]-[0059]); and in Minami’s Figures 2 and 5, the power level of the signal reflected from the coupler CP1 is used as a reference to evaluate the signal levels/loss/attenuations of different fiber paths (Figure 2, at Distance 0 “CP1”, the power is normalized to “1”, or P/P0 is 1; and all other signal levels reflected from different paths/points are relative to or compared with the power level “1” reflected by CP1); then, the scheme or processes used for calculate a value representative of the absolute loss of each branch also can be applied to the system of combined Lam et al and Minami et al and Nakajima et al.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Daems to the system/method of Lam et al and Minami et al and Nakajima et al so that accurate calibrated reflective signals for use as a reference for determining an attenuation for each optical fiber can be obtained, and fault events and position at faults can be accurately identified.
6). With regard to claim 17, Lam et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 16 above. And the combination of Lam et al and Minami et al and Nakajima et al and Daems further discloses wherein the OTDR is optically connected to the N optical fibers to extract, from each optical fiber of the N optical fibers, information by analyzing signals returned from the N optical fibers (Lam: Abstract, and column 3 line 61 to column 4 line 17; Figure 4, step 435, column 7 line 33-39. Minami: Figures 2-6 etc. Nakajima: Figures 4, 11-12 and 16 etc.).
7). With regard to claim 18, Lam et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 16 above. And the combination of Lam et al and Minami et al and Nakajima et al and Daems further discloses wherein the OTDR is optically connected to the N optical fibers to compare, for the N optical fibers, N simultaneous test results to a reference test result to identify changes on at least one optical fiber under test of the N optical fibers (Lam: column 7 line 33-52, “A reference test signature is stored for each optical splitter 310. The reference signature may be obtained during testing conducted after the initial fiber plant and during subsequent service intervals when new ONUs 115 are added to a given subset. The reference test signatures characterize each subset of pt-2-pt fiber links 145 as a unique test PON. If a new reflection peak is present in the newly acquired reflection signature 505 and an existing peak in the reference reflection signature 510 is either gone or smaller, then a fiber fault can be assumed to be present in the associated fiber link 145. If the newly acquired reflection signature 505 is identical to the stored reference reflection signature 510, then it can be assumed that the loss of service is due to an error in the CPE and not in the fiber plant.” Minami: Figure 2 can be viewed as a reference test result waveform, and Figure 2 shows that ED2’ peak, which is due to “ED2 … is shifted to a location of a terminal point ED2' on the waveform”, and “a fault distance matches with a shift distance by which the location of the terminal point ED2 at the time tk is shifted to the location of the terminal point ED2' at the time tk+1” column 6 lines 18-44; “the fault determination is made by comparing results of the separative analysis, which are obtained at the measuring times respectively. By the fault determination, it is possible to determine a fault line and a fault location (or fault distance) as well as a fault time” column 2 line 64 to column 3 line 3. Nakajima: Figures 1, 4-7, 11-12 and 16 etc.).
8). With regard to claim 22, Lam et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 16 above. And the combination of Lam et al and Minami et al and Nakajima et al and Daems further discloses wherein the OTDR operates at a different wavelength (Lam: wavelength associated with OTDR 135) than a traffic wavelength (Lam: wavelengths associated with the OLT TX/RX 125; column 4 lines 50-56. In Figure 22, Nakajima discloses that the OTDR operates at a different wavelength than a traffic wavelength. Daems also discloses “a separate optical test equipment 8 is provided, such as an OTDR, that operates at a different wavelength (for example the test equipment 8 operates at a wavelength of 1625 nm) than the service equipment 2 (e.g. that operates at 1490, 1550 nm when the network is operational)”, [0044]-[0045]).
9). With regard to claim 23, Lam et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 16 above. And the combination of Lam et al and Minami et al and Nakajima et al and Daems further discloses the optical fiber monitoring apparatus according to claim 16, further comprising a wavelength dependent multiplexer (e.g., Lam: wavelength selective 3-port optical couplers 210; and Daems: WDM 4 in Figure 2) to insert a test signal (also refer Figure 22 of Nakajima).
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Lam et al and Minami et al and Nakajima et al and Daems as applied to claim 1 above, and in further view of Perry (US 2023/0013084).
Lam et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 1 above. But, Lam et al and Minami et al and Nakajima et al and Daems do not expressly disclose the optical fiber monitoring apparatus according to claim 1, further comprising: N optical fibers of different lengths optically inserted between the N test port optical fiber outputs and N optical fibers including the optical fiber, wherein the N optical fibers are optically connected to the N test port optical fiber outputs.
However, to introduce N delay fibers into the transmission paths for OTDR is a common practice. E.g., Perry discloses a system/method to monitor optical fibers. As shown in Figure 2F, 4 optical fibers of different lengths (287a-287d) optically inserted between a N test port optical fiber outputs (splitter multi ports) and N optical fibers (284a-284d) including the optical fiber (284), wherein the N optical fibers are optically connected to the N test port optical fiber outputs (Figure 2F).
It is also worth to point out that Perry also discloses that dedicated reflectors are implemented at the end of each fiber (Figure 1: at the End Equip 207; Figure 2F: the terminating connectors 289); “installation and/or maintenance teams dispatched to the field for installation and/or maintenance may conduct supplemental OTDR measurements on the entire PON 211 and/or segments of the PON 211, such as the first optical fiber 202 and/or the distal optical fibers 206. Results, including cable lengths, may be stored and/or otherwise retained in PON configuration records. Similarly, the timing offsets of the output ports 205 of the splitter 203 may be measured and/or otherwise determined according to specification sheets, calibration records, manufacturing records, and the like” ([0059]); “the timing offset values may be determined at a time of manufacture, e.g., curing a characterization or performance test and/or calibration procedure.” ([0075]); “It is understood that a device characterization and/or calibration procedure by which the delay values are determined may be performed at a time of manufacture and/or at a time of installation or perhaps even post installation. For example, a test pulse may be injected into the input, e.g., port 0, and divided into four pulse signal segments, one at each of the output ports, e.g., ports 1-4. A time difference may be measured and/or otherwise calculated based on measured time differences between injection of the input test pulse and detective of the respective output test pulses. The resulting delay measurements may be recorded and/or otherwise noted, e.g., in association with the particular optical splitter device serial number, to the extent the results may vary from device to device” ([0090]); as shown in Figure 2B, “The example OTDR trace 227 represents a graphical signature of an optical fiber network, e.g., PON 211 (FIG. 2A). The trace 227 indicates attenuation along a length of the optical fiber, which provides insight into the performance of the link components (cable, connectors, and splices) and the quality of an installation by examining non-uniformities in the OTDR trace 220” ([0053]-[0054]); and “According to the illustrative PON 211, the fourth, fifth and sixth events 223d, 223e, 223f correspond to fiber terminations at the ONTs 207” ([0058]); and then Figure 2C shows “The example trace 237 is presented as a graph with magnitude along a vertical axis 231 and time along a horizontal axis 232. In particular, the trace 237 represents a trace obtained from the same PON 211, to permit a comparison to the initial trace 227 (FIG. 2B) obtained during normal operating conditions, e.g., at a time of installation and/or reconfiguration. Any changes to the PON 211 that may result from breaks, bends, stretches and/or configuration changes, are observable as differences between the initial trace 227 and the example subsequent trace 237” ([0063]); therefore, Figure 2B of Perry is also “calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”; as shown in Figure 2C, the original event 233e “does not appear in the subsequent trace 237”, instead a new event 236 comes.
As disclosed by Perry, “The optical delay devices provide distinguishable delay values, that delay the divided portions of the optical signal, the distinguishable delay values facilitating associations of the PON segments to the output ports based on optical time domain reflectometry (OTDR) measurements obtained via the input port” (Abstract, and [0089]-[0096]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use fiber delays as taught by Perry to the system/method of Lam et al and Minami et al and Nakajima et al and Daems so that distinguishable delay values/events can be obtained and identified, and coincidence of reflected pulses from different fibers under test can be avoided.
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Lam et al and Minami et al and Nakajima et al and Daems as applied to claim 1 above, and in further view of Perry (US 2023/0013084) and Martel et al (US 2020/0252125).
Lam et al and Minami et al and Nakajima et al and Daems discloses all of the subject matter as applied to claim 1 above. And Lam et al and Minami et al and Nakajima et al and Daems disclose wherein the N optical fibers are optically connected to the N test port optical fiber outputs (Lam: Figure 3 and Figure 6. Figure 1 of Minami. Nakajima: Figures 1, 5-7 and 22).
But, Lam et al and Minami et al and Nakajima et al and Daems do not expressly disclose the optical fiber monitoring apparatus according to claim 1, further comprising: N antennas connected to N optical fibers including the optical fiber.
However, it is obvious to one skilled in the art that the system/method disclosed by Lam et al and Minami et al and Nakajima et al and Daems can be used for Radio-over-Fiber (RoF) system/method, in which antennas are connected to optical fibers, respectively. E.g., Perry discloses a multi-path OTDR system (Figure 2A) functioning within the communication network of Figure 1 ([0007] and [0039]); and Figure 1 can be the distributed antennas networks ([0161], “the distributed antennas networks shown in FIG. 1(s) that enhance wireless service coverage by providing more network coverage”, and [0035]), and the end equipment can be antennas (e.g., 122 in Figure 1). Another prior art, Martel et al, also discloses a system/method in which N antennas connected to N optical fibers (Figure 1, and [0024]-[0028] etc., “send an optical probe signal to the particular RRH 12, 14, 16 and receive a back-reflected signal to perform fiber monitoring testing (e.g., OTDR)”, the RRH 12/14/16 are remote radio head, or antenna).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Perry and Martel et al to the system/method of Lam et al and Minami et al and Nakajima et al and Daems so that the OTDR can be used to monitor the radio-over-fiber system.
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Lam et al and Minami et al and Nakajima et al and Daems as applied to claim 1 above, and in further view of Smith et al (US 2013/0259469) and Kim et al (US 2011/0026923).
Lam et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 1 above. But, Lam et al and Minami et al and Nakajima et al and Daems do not expressly disclose wherein the OTDR is a multi-wavelength OTDR, further comprising: a multi-wavelength multiplexer/demultiplexer optically inserted between the OTDR and the plurality of 1 x N independent splitters.
However, an OTDR that outputs a plurality of wavelength is known in the art. E.g., Smith et al discloses a system/method to monitor a passive optical network (PON). As shown in Figures 4-6, an OTDR can send multiple wavelengths; and a multi-wavelength multiplexer/demultiplexer (e.g., 510) can be used to demultiplex the output from the OTDR and multiplex reflected signals from the fibers under test. In Figure 5, Smith et al does not expressly show a plurality of splitters connected to the output ports of the multiplexer/demultiplexer (e.g., 510/515). However, fist, the primary reference Lam et al discloses that each output from the optical switch (215) can connect to a splitter (310), and Minami and Nakajima et al disclose that a splitter can be inserted between the OTDR and a plurality of 1 x N splitters. Second, another prior art, Kim et al, discloses a WDM-TDM-PON (Figures 2 and 23 etc.), as shown in Figures 2 and 23, optical splitters (205 in Figure 2, or the 1:M splitters in Figure 23) are connected to a multi-wavelength multiplexer/demultiplexer (Muc/Demux). By using the WDM-TDM structure with splitters, the optical line terminal (OLT) can reach more ONUs or clients grouped by splitters. And Kim et al also discloses that a monitoring structure similar to the OTDR can be installed in the OLT (Figures 27 and 29), as shown in Figure 29, a plurality of wavelengths are outputs from the multiplexer 2665 and sent downstream for monitoring fibers.
By using different wavelengths and each splitter associating with one wavelength, reflected pulses on different wavelengths, which arrive the detector at the same time, are distinguishable due to their different wavelengths. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Smith et al and Kim et al to the system/method of Lam et al and Minami et al and Nakajima et al and Daems so that a multiplexer/demultiplexer, instead of a splitter, is used between the OTDR and the plurality of 1 x N splitters, and a WDM-TDM OTDR (WDM+Splitters) can be obtained and the functions of the system/method is enhanced.
Claims 10-13 and 15 are rejected under 35 U.S.C. 103 as being unpatentable over Lam et al (US 9,240,855) in view of Chen et al (US 9,435,712) and Minami et al (US 6,310,702) and Nakajima et al (US 2009/0190921) and Daems (US 2011/0268438).
1). With regard to claim 10, Lam et al discloses an optical fiber monitoring apparatus (Figures 1-3 and 6) comprising:
an OTDR (e.g., OTDR 135; or the combination of OTDR 135 and the switch 215) including an OTDR optical source (the optical source in OTDR 135, which “launch the optical test signal”, in Figures 1-3), wherein the OTDR is optically connected to N optical fibers (fibers 145), each having dedicated reflectors (demarcation devices 150 as shown in Figure 1; “demarcation devices 150 each include a wavelength selective reflector that is reflective to the optical test signal output by OTDR unit 135 (e.g., in the 1625-1670 nm optical band) while transmissive to the upstream and downstream data signals communicated between OLT 125 and ONUs 115 (e.g., 1310 nm upstream and 1490 nm downstream)”, column 4 lines 43-56) connected to an end (Figure 1, column 4 lines 43-56) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (column 7 line 33-52, and steps 425-440, “In a process block 435, the reflection signature is analyzed to determine if a fiber fault exists, and if so, where the fiber fault is located. In one embodiment, the reflection signature is analyzed by comparing it to a reference reflection signature stored for the given test PON (i.e., selected optical splitter 310). FIG. 5B illustrates an example reference signature 510. A reference test signature is stored for each optical splitter 310. The reference signature may be obtained during testing conducted after the initial fiber plant and during subsequent service intervals when new ONUs 115 are added to a given subset. The reference test signatures characterize each subset of pt-2-pt fiber links 145 as a unique test PON. If a new reflection peak is present in the newly acquired reflection signature 505 and an existing peak in the reference reflection signature 510 is either gone or smaller, then a fiber fault can be assumed to be present in the associated fiber link 145. If the newly acquired reflection signature 505 is identical to the stored reference reflection signature 510, then it can be assumed that the loss of service is due to an error in the CPE and not in the fiber plant”. As shown in Figure 5A, when compared with Figure 5B, an “original signature peak disappears due to fiber break” at the location/distance shown in vertical dotted line, and a new peak is present at “Reflection Due to fiber fault”; and step 435 in Figure 4 is “Analyze Reflection Signature (E.G., Compare to Reference Signature)”; that is, Figure 5B is a reference signature (510), or is a type of calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers), wherein N is greater than one (Figures 2-3 and 6, more than one fibers connected to each splitter), and
wherein the OTDR is a multi-channel OTDR (Figure 3, the switch has N outputs, which correspond to N channels) having multiple, parallel inputs/outputs (1:N switch, N parallel inputs/outputs) each coupled through a dedicated optical fiber (fiber between the switch 215 and a splitter 310) to one of a plurality of 1 x N an independent splitters (e.g., one of the N splitters 310);
an OTDR optical receiver (the receiver in the OTDR 135, which detect/retrieves the “test signal reflections”); and
a 1 x N optical splitter (e.g., optical splitter 310 in Figure 3), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., any one of the 1:M optical splitter is one of the N 1:M optical splitters 310);
wherein N is greater than one (1:M, M is greater than 1),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (M outputs. Column 6 lines 10-43), and
wherein each test port optical fiber output is optically connectable to an optical fiber (Figure 3, to fibers 145, respectively) to optically connect the optical fiber to the OTDR optical source and the OTDR optical receiver (Figure 3) for simultaneous monitoring of each test port optical fiber output by the OTDR (all the fibers connected to the splitter 310 at the left side are monitored simultaneously. Column 6 lines 10-43).
But, in Figures 1-3 and 6, Lam et al does not expressly show the detail inside the OTDR, or Lan et al does not expressly disclose: an optical coupler optically inserted between the OTDR optical source, the OTDR optical receiver, and the 1 x N optical splitter; and Lam et al also does not expressly disclose wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate to implement a plurality of splitting ratios, and wherein the OTDR is a simultaneous multi-channel OTDR having multiple, parallel inputs/outputs each coupled through a dedicated optical fiber to an independent splitter for simultaneous monitoring of each test port optical fiber output by the OTDR; and Lam et al also does not expressly use the phrase “calibrated” to describe the Figure 5B.
Regarding the optical coupler and optical source and receiver etc., however, to implement a coupler in the OTDR so that one port is used to send a test signal out and receive reflected signal is well known in the art. E.g., Chen et al discloses an optical transmission system/method with OTDR, as shown in Figure 3, the OTDR includes an optical coupler (340) optically inserted between the OTDR optical source (310/320), the OTDR optical receiver (330), and an 1 x N optical splitter (120 in Figure 1).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use a coupler as taught by Chen et al to the OTDR of Lam et al so that the test signal can be conveniently sent to a splitter and reflected signals can be properly directed to a detector/receiver via a common port of the coupler.
Regarding the simultaneous multi-channel OTDR and the splitters with a plurality of splitting ratios, in Figure 3 or Figure 6 of Lam et al, a single OTDR and one switch are used, and because of the switch, at one time only one specific splitter is connected to the OTDR or only one group of fibers are connected to the OTDR, and other groups of fibers (connected to other splitters) cannot be simultaneously monitored since the single OTDR can only be connected to one group of fibers at one time. E.g., in Figure 3, while the switch (215) is connected to the left side splitter (310), the splitter 310 is connected to multiple (M) fibers, and all the fibers 1-M are monitored simultaneously by the OTDR; and when the switch (215) is connected to the right side splitter (310), the splitter 310 is connected to multiple (M) fibers (e.g., another group of fibers), and all the fibers corresponding to right side splitter are monitored simultaneously by the OTDR.
However, to use a splitter, instead of a switch, to monitor a large number of fiber links simultaneously by a single OTDR are known in the art. E.g., Minami et al discloses a testing apparatus (Figure 1 etc.) for simultaneous monitoring of each test port optical fiber (C1, C2, D1, D2 and D3) output by the OTDR (Figures 2 and 5 etc.).
As shown in Figure 1 of Minami et al, or Figure O3 above, which is adapted from Minami’s Figure 1 and the dotted box is added to show the structure corresponding to claimed “multi-channel OTDR”, the multi-channel OTDR is a simultaneous multi-channel OTDR having multiple, parallel inputs/outputs (e.g., the outputs of the coupler CP1, which is a “branch” device, or a splitter, “the optical fiber CP1 wherein it is subjected to branching into two directions”, column 3 line 46 to column 4 line 19) each coupled through a dedicated optical fiber (B1 and B2) to one of a plurality of independent splitters (CP2 and CP3), wherein the plurality of independent splitters (CP2 and CP3) includes the 1x2 splitter (CP2), and further wherein each test port optical fiber output is optically connectable to an optical fiber (C1, C2, D1, D2, or D3) to optically connect the optical fiber to the OTDR for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 2-6). In Figure 1 of Minami et al, the independent splitters CP2 and CP3 may have different splitting ratio: e.g., CP2 is 1:2, and CP is 1:3.
Another prior art, Nakajima et al, discloses an an optical fiber monitoring system/method (Figures 1 and 22 etc.) comprising:
an OTDR (2 in Figure 1, [0170], “an OTDR (Optical Time Domain Reflectometer) is used as the test apparatus 2, and ONUs (Optical Network Units) are used as the terminators 4 is described”) including an OTDR optical source (the optical source that sends the light to the fiber f1/splitter 3a; [0010], “an OTDR test apparatus (including a light source) 1122 for utilizing backscattering light to measure a loss of the optical fiber and to detect a failure and a location of failure”), wherein the OTDR is optically connected to N optical fibers (f5-f6, or f7-f9), each having dedicated reflectors terminators 4a-4f etc. in Figures 1 and 5-7 etc., Abstract, and [0107]-[0113] etc.; e.g., fiber f5 has a reflector/terminator 4a, and fiber f6 has a reflector/terminator 4b. Figure 22, [0237], “the optical fiber lengths from the measurement apparatus 350 to the respective ONUs 420-1 to 420-N as the terminators are previously designed to be different when the optical fibers are deployed.”) connected to an end (Figures 1 and 5-7, terminator. Figure 22, the ONU) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (Abstract, and [0117]-[0122] etc., “In the normal information recording portion 14b, information with regard to intensities of the reflected lights which, after being emitted from the test apparatus 2 via the splitters 3, are reflected and returned by the respective terminators 4 is previously recorded. The intensities of the reflected lights recorded in this normal information recording portion 14b are those from the respective terminators 4 in the case where there is no failure in the optical lines f (f1 to f10)”, and “The attenuation amount determination portion 15 determines by how much the reflected light intensity of the predetermined terminator 4 previously recorded in the normal information recording portion 14b is attenuated from the corresponding reflected light intensity recorded in the monitored information recording portion 14c. Furthermore, the attenuation amount determination portion 15 determines whether or not the attenuated amount is equal in value to the attenuated amount of the other terminators 4 belonging to the same group”. And Figure 3, “one example of group information recorded in the group information recording portion 14a. As shown in the figure, information with regard to the terminators 4 connected to the same splitter 3 is recorded as group information, classified for every group. For example, the terminators 4a, 4b connected to the splitter 3b are recorded as in group g1”), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”), and
wherein the OTDR is a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a forms a multi-channel OTDR, which has three parallel inputs/outputs associated with fibers f2, f3 and f4) having multiple, parallel inputs/outputs (e.g., the three parallel inputs/outputs for the fibers f2-f4) each coupled through a dedicated optical fiber to one of a plurality of 1 x N independent splitters (3b-3d in Figure 1 etc.);
an OTDR optical receiver ([0109], “The test apparatus 2 emits an optical signal to the splitter 3a and receives an optical signal emitted by the splitter 3a via the optical line f1 based on the control by the optical line monitoring apparatus 1”, it is inherent that an OTDR optical receiver is in the test apparatus 2); and
wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., the splitter 3b), wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate ([0110], “As a splitter 3, for example a PLC (Planar Lightwave Circuit) type splitter can be used in which optical waveguides are branched in a tree-like manner on a silica substrate”, and [0184]) to implement a plurality of splitting ratios (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”);
wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (e.g., the splitter 3b has two test port optical fiber outputs), and
wherein each test port optical fiber output is optically connectable to an optical fiber (e.g., the two test ports of the splitter 3b is optically connectable to two optical fibers f5 and f6, respectively) to optically connect the optical fiber to the OTDR optical source and the OTDR optical receiver for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 1 and 5-7 etc. and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”).
That is, Nakajima et al discloses a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a, which has three parallel inputs/outputs associated with fibers f2, f3 and f4) has three parallel inputs/outputs each coupled through a dedicated optical fiber (f2, or f3, or f4) to one of a plurality of 1 x N independent splitters (3b-3d); and the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate to implement a plurality of splitting ratios ([0184], and Figure 1 etc.).
As disclosed by Minami et al and Nakajima et al, by using one more splitter, which is connected to another stage of splitters, the OTDR can monitor a large number of fibers simultaneously, and all the fibers connected to the splitters are simultaneous monitored. That is, the combination of Lam et al and Minami et al and Nakajima et al teaches/suggests wherein the OTDR is a simultaneous multi-channel OTDR having multiple, parallel inputs/outputs each coupled through a dedicated optical fiber to an independent splitter, and further wherein each test port optical fiber output is optically connectable to an optical fiber to optically connect the optical fiber to the OTDR for simultaneous monitoring of each test port optical fiber output by the OTDR. Figure O4 above is a diagram showing the combination of Lam et al and Minami et al and Nakajima et al.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Minami et al and Nakajima et al to the system/method of Lam et al and Chen et al so that all the fibers (channels) can be monitored at the same time, and the system capacity is increased, and the functions of the monitoring system is enhanced; and by implementing the splitters having a plurality of splitting ratio implemented on a PLC, a compact, high reliable, excellent uniform (even power split), low wavelength dependent splitting assembly (having a plurality of splitters) can be obtained, and the splitting assembly is highly scalable to many channels.
Regarding the calibrated reflective signals, as discussed above, the reference reflection signature 510 shown in Figure 5B is a type of “calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers” because the reflection signature 510 is “obtained during testing conducted after the initial fiber plant and during subsequent service intervals when new ONUs 115 are added to a given subset” and for comparison determining an attenuation (disappearance) and fault for each of the N optical fibers. Also, for the testing apparatus shown in Figure 1 etc., Minami et al discloses that each optical fiber has a dedicated reflector (EC1, EC2, ED1, ED2 and ED3); and “FIG. 2 is a graph showing a response waveform representing response light containing reflection beams and back scattering beams, which are measured by an OTDR measurement device shown in FIG. 1 before occurrence of fault” (column 3 lines 16-19); “a vertical axis of FIG. 2 represents a level of the response light which is a mixture of the reflection beams and back scattering beams given from the optical fibers A to D3 respectively. A spike wave emerges at each of points of the waveform of FIG. 2 which correspond to the terminal points EC1, EC2, ED1, ED2 and ED3 of the optical fibers C1, C2, D1, D2 and D3 respectively. This spike wave is produced based on Fresnel reflection. The terminal point EC1 is located optically in the closest proximity to the OTDR measurement device MS1. So, other terminal points are located with different distances from the OTDR measurement device MS1, wherein locations of them become farther from the device MS1 in an order of ED1, ED2, ED3 and EC2. That is, the terminal point EC2 is located at the farthest place from the device MS1” (column 4 lines 49-64); “With regard to record events that are recorded in connection with the measurement times lying between t1 and tk, there occurs no change in optical power, so it is possible to make a decision that an abnormal state does not exist. With regard to record events that are recorded in connection with the measurement times of tk and tk+1, a change occurs in optical power, so it is possible to make a decision that an abnormal state exists. Based on the time that the abnormal state occurs, it is possible to calculate a fault distance (or fault location) with ease”. That is, Fig. 2 is an initial measurement, and is a baseline to be compared when any other events occur. As shown in Figure 5, an event “ED2’ ” occurs. And Nakajima also teaches to compare reflected signals with the recorded normal information so to determine whether an abnormal state exists (Figures 4, 11-12 and 16 etc.).
As shown in Figure O2 above, “the location of the terminal point ED2 of the optical fiber D2 on the waveform (see FIG. 2), which is measured at the time tk, is shifted to a location of a terminal point ED2' on the waveform (see FIG. 5), which is measured at the time tk+1. So, it can be estimated that a fault occurs in an interval of time between tk and tk+1. In addition, a fault line on which the fault occurs matches with the optical fiber D2 whose terminal point is shifted as described above. Further, a fault distance matches with a shift distance by which the location of the terminal point ED2 at the time tk is shifted to the location of the terminal point ED2' at the time tk+1” (column 6 lines 19-44); Minami’s Figure 2 shows the measured power level (attenuation) of reflected signal vs fiber distance; the longer the fiber, the signal intensity is attenuated more; and when a fault occurs on fiber D2, the original signal ED2 is completed “attenuated” or disappeared, and a new signal at ED2’ comes; therefore, what are showed in Figure 2, which are measured “before occurrence of fault”, are calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers. Then, the processing to obtain the waveform shown in Figure 2 and the purpose/usage of Figure 2 are actually making the Figure 2 be “calibrated reflective signals used as a reference for determining an attenuation (or power level) for each of the N optical fibers”. Another prior art, Daems, also discloses a system/method for “ABSOLUTE OPTICAL ATTENUATION MEASUREMENT WITH OTDR” (title), and “Devices and methods for optical measurements in point-to-point and point-to-multipoint networks, e.g. like PON networks with splitters are described in which reflected power from some known reflections at the end of the lines is used to determine the attenuation and stability of the attenuation of each line” (Abstract). As shown in Figures 2 and 4 etc., reflectors (14 and 16 in Figure 2, or Ref R1 and Ref R2 in Figure 4; [0042]-[0045] and [0059] etc.) are implemented at the end of fibers, and “FIG. 4 shows how test equipment in accordance with the present invention can be calibrated” ([0029]) and “This calibration can be done when setting up the optical network. Once calibrated, the measurement of absolute loss can be done without further use of power meters” ([0059]); and “Accurate loss measurements are possible from just one side of the network through the splitter” ([0064]); and “It can be understood from the above that the measured absolute values of loss are obtained by methods and devices according to the present invention. As an extension of the present invention, the network can be monitored over time and changes in loss can be detected, e.g. as caused by a sharp bend introduced into a fiber. The measurement of absolute loss allows a change over time to be detected, whereas relative methods may suffer from changes in conditions between measurements which alter the result”; therefore, Daems teaches/suggests “dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”. In Figures 2 and 4, Daems uses the power level of the signal reflected from the retuning device 10 as a reference to calculate the “absolute loss” of each branch ([0049]-[0059]); and in Minami’s Figures 2 and 5, the power level of the signal reflected from the coupler CP1 is used as a reference to evaluate the signal levels/loss/attenuations of different fiber paths (Figure 2, at Distance 0 “CP1”, the power is normalized to “1”, or P/P0 is 1; and all other signal levels reflected from different paths/points are relative to or compared with the power level “1” reflected by CP1); then, the scheme or processes used for calculate a value representative of the absolute loss of each branch also can be applied to the system of combined Lam et al and Minami et al and Nakajima et al.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Daems to the system/method of Lam et al and Minami et al and Nakajima et al so that accurate calibrated reflective signals for use as a reference for determining an attenuation for each optical fiber can be obtained, and fault events and position at faults can be accurately identified.
2). With regard to claim 11, Lam et al and Chen et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 10 above. And the combination of Lam et al and Chen et al and Minami et al and Nakajima et al and Daems further discloses wherein the OTDR optical source includes a laser (e.g., laser 310 in Chen).
3). With regard to claim 12, Lam et al and Chen et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 10 above. And the combination of Lam et al and Chen et al and Minami et al and Nakajima et al and Daems further discloses wherein the OTDR optical receiver includes a photodiode (e.g., 330 in Chen).
4). With regard to claim 13, Lam et al and Chen et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claim 10 above. And the combination of Lam et al and Chen et al and Minami et al and Nakajima et al and Daems further discloses wherein the optical coupler is an M-port optical coupler (e.g., 3-port optical coupler 340 in Chen).
5). With regard to claim 15, Lam et al and Chen et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claims 10 and 13 above. And the combination of Lam et al and Chen et al and Minami et al and Nakajima et al and Daems further discloses wherein M is equal to three (Chen: 3-port coupler 340).
Claim 14 is rejected under 35 U.S.C. 103 as being unpatentable over Lam et al and Chen et al and Minami et al and Nakajima et al and Daems as applied to claims 10 and 13 above, and in further view of Husbands (US 4,449,043).
Lam et al and Chen et al and Minami et al and Nakajima et al and Daems discloses all of the subject matter as applied to claims 10 and 13 above. But, Lam et al and Chen et al and Minami et al and Nakajima et al and Daems do not expressly disclose wherein the optical coupler includes an additional output connected to an additional measurement port.
However, to add additional port to a coupler for additional purpose is known in the art. E.g., Husbands discloses a system/method to monitor fiber connections etc. As shown in Figure 1, instead of a 3-port coupler, a 4-port coupler is used: port 28 for light source, port 30 for receiving reflected signals, port 34 for transmission/receiving (common port), an additional output (B) connected to an additional measurement port (32, for monitoring the output signals).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Husbands to the system/method of Lam et al and Chen et al and Minami et al and Nakajima et al and Daems so that additional port can be used for additional/auxiliary purpose to enhance the function of the system/method.
Claims 24-25 are rejected under 35 U.S.C. 103 as being unpatentable over Lam et al and Minami et al and Nakajima et al and Daems as applied to claims 1 and 16 above, and in further view of Chen et al (US 9,435,712).
Lam et al and Minami et al and Nakajima et al and Daems disclose all of the subject matter as applied to claims 1 and 16 above. And the combination of Lam et al and Minami et al and Nakajima et al and Daems further discloses the optical fiber monitoring apparatus according to claims 1 and 16, further comprising a receiver (because it is an OTDR, it is inherent that a receiver is in the OTDR so to detect the reflected signals. Nakajima: [0109], “The test apparatus 2 emits an optical signal to the splitter 3a and receives an optical signal emitted by the splitter 3a via the optical line f1 based on the control by the optical line monitoring apparatus 1”, it is inherent that an OTDR optical receiver is in the test apparatus 2).
But, Lam et al and Minami et al and Nakajima et al and Daems do not expressly show the detail inside the OTDR, or Lam et al and Minami et al and Nakajima et al and Daems do not expressly show a photodiode is in the receiver.
However, Chen et al discloses an optical transmission system/method with OTDR, as shown in Figure 3, the OTDR includes an optical coupler (340) optically inserted between the OTDR optical source (310/320), the OTDR optical receiver (330), and an 1 x N optical splitter (120 in Figure 1). And the OTDR optical receiver includes a photodiode (e.g., 330).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Chen et al to the OTDR of Lam et al and Minami et al and Nakajima et al and Daems so that the reflected test/monitoring signal can be properly detected.
Claims 1- 3, 16-18 and 22 are rejected under 35 U.S.C. 103 as being unpatentable over Nakajima et al (US 2009/0190921) in view of Minami et al (US 6,310,702) and Daems (US 2011/0268438).
1). With regard to claim 1, Nakajima et al discloses an optical fiber monitoring system/method (Figures 1 and 22 etc.) comprising:
an optical time domain reflectometer (OTDR) (2 in Figure 1, [0170], “an OTDR (Optical Time Domain Reflectometer) is used as the test apparatus 2, and ONUs (Optical Network Units) are used as the terminators 4 is described”), wherein the OTDR is optically connected to N optical fibers (f5/f6, or f7-f9), each having dedicated reflectors (terminators 4a-4f etc. in Figures 1 and 5-7 etc., Abstract, and [0107]-[0113] etc.; e.g., fiber f5 has a reflector/terminator 4a, and fiber f6 has a reflector/terminator 4b. Figure 22, [0237], “the optical fiber lengths from the measurement apparatus 350 to the respective ONUs 420-1 to 420-N as the terminators are previously designed to be different when the optical fibers are deployed.”) connected to an end (Figures 1 and 5-7, terminator. Figure 22, the ONU) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (Abstract, and [0117]-[0122] etc., “In the normal information recording portion 14b, information with regard to intensities of the reflected lights which, after being emitted from the test apparatus 2 via the splitters 3, are reflected and returned by the respective terminators 4 is previously recorded. The intensities of the reflected lights recorded in this normal information recording portion 14b are those from the respective terminators 4 in the case where there is no failure in the optical lines f (f1 to f10)”, and “The attenuation amount determination portion 15 determines by how much the reflected light intensity of the predetermined terminator 4 previously recorded in the normal information recording portion 14b is attenuated from the corresponding reflected light intensity recorded in the monitored information recording portion 14c. Furthermore, the attenuation amount determination portion 15 determines whether or not the attenuated amount is equal in value to the attenuated amount of the other terminators 4 belonging to the same group”. And Figure 3, “one example of group information recorded in the group information recording portion 14a. As shown in the figure, information with regard to the terminators 4 connected to the same splitter 3 is recorded as group information, classified for every group. For example, the terminators 4a, 4b connected to the splitter 3b are recorded as in group g1”. That is, the “normal information” is used as a reference for determining an attenuation for each optical fibers, and the “normal information” can be viewed as a “calibrated” reflective signal), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”); and
a 1 x N optical splitter (e.g., the splitter 3b in Figure 1, or 410 in Figure 22) that is optically connected to the OTDR (Figures 1 and 22 etc.), wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate ([0110], “As a splitter 3, for example a PLC (Planar Lightwave Circuit) type splitter can be used in which optical waveguides are branched in a tree-like manner on a silica substrate”, and [0184]) to implement a plurality of splitting ratios (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (e.g., the splitter 3b has two test port optical fiber outputs), and
wherein the OTDR is a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a forms a multi-channel OTDR, which has three parallel inputs/outputs associated with fibers f2, f3 and f4), having multiple parallel inputs/outputs (e.g., the three parallel inputs/outputs for the fibers f2-f4) each coupled through a dedicated optical fiber (one of the f2, f3, or f4) to one of a plurality of 1 x N independent splitters (3b-3d in Figure 1 etc.), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., the splitter 3b), and further wherein each test port optical fiber output is optically connectable to an optical fiber (e.g., the two test ports of the splitter 3b is optically connectable to two optical fibers f5 and f6, respectively) to optically connect the optical fiber to the OTDR for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 1 and 5-7 etc. and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”).
Nakajima et al does not use the word “calibrated” to label the “normal information”; however, as discussed above, the “normal information” is used as a reference for determining an attenuation for each optical fibers; therefore the “normal information” is a type of “calibrated” reflective signal. Another prior art, Daems, also discloses a system/method for “ABSOLUTE OPTICAL ATTENUATION MEASUREMENT WITH OTDR” (title), and “Devices and methods for optical measurements in point-to-point and point-to-multipoint networks, e.g. like PON networks with splitters are described in which reflected power from some known reflections at the end of the lines is used to determine the attenuation and stability of the attenuation of each line” (Abstract). As shown in Figures 2 and 4 etc., reflectors (14 and 16 in Figure 2, or Ref R1 and Ref R2 in Figure 4; [0042]-[0045] and [0059] etc.) are implemented at the end of fibers, and “FIG. 4 shows how test equipment in accordance with the present invention can be calibrated” ([0029]) and “This calibration can be done when setting up the optical network. Once calibrated, the measurement of absolute loss can be done without further use of power meters” ([0059]); and “Accurate loss measurements are possible from just one side of the network through the splitter” ([0064]); and “It can be understood from the above that the measured absolute values of loss are obtained by methods and devices according to the present invention. As an extension of the present invention, the network can be monitored over time and changes in loss can be detected, e.g. as caused by a sharp bend introduced into a fiber. The measurement of absolute loss allows a change over time to be detected, whereas relative methods may suffer from changes in conditions between measurements which alter the result”; therefore, Daems teaches/suggests “dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”. In Figures 2 and 4, Daems uses the power level of the signal reflected from the retuning device 10 as a reference to calculate the “absolute loss” of each branch ([0049]-[0059]); and in Minami’s Figures 2 and 5, the power level of the signal reflected from the coupler CP1 is used as a reference to evaluate the signal levels/loss/attenuations of different fiber paths (Figure 2, at Distance 0 “CP1”, the power is normalized to “1”, or P/P0 is 1; and all other signal levels reflected from different paths/points are relative to or compared with the power level “1” reflected by CP1); then, the scheme or processes used for calculate a value representative of the absolute loss of each branch also can be applied to the system of Nakajima et al.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Daems to the system/method of Nakajima et al so that accurate calibrated reflective signals for use as a reference for determining an attenuation for each optical fiber can be obtained, and fault events and position at faults can be accurately identified.
2). With regard to claim 2, Nakajima et al and Daems disclose all of the subject matter as applied to claim 1 above. And the combination of Nakajima et al and Daems further discloses wherein the OTDR is optically connected to N optical fibers including the optical fiber to extract, from each optical fiber of the N optical fibers (Figures 1 and 5-7 and 22 etc.), information by analyzing signals returned from the N optical fibers to the N test port optical fiber outputs (Nakajima: Figures 4, 11-12 and 16 etc., [0117]-[0122] etc.)
3). With regard to claim 3, Nakajima et al and Daems disclose all of the subject matter as applied to claim 1 above. And the combination of Nakajima et al and Daems further discloses wherein the OTDR is optically connected to N optical fibers including the optical fiber to compare, for the N optical fibers, N simultaneous test results to a reference test result to identify changes on at least one optical fiber under test of the N optical fibers (Nakajima: Figures 1, 4-7, 11-12 and 16 etc.; [0117]-[0122] and [0127] etc.).
4). With regard to claim 16, Nakajima et al discloses an optical fiber monitoring apparatus (Figures 1 and 22 etc.) comprising:
an optical time domain reflectometer (OTDR) (2 in Figure 1, [0170], “an OTDR (Optical Time Domain Reflectometer) is used as the test apparatus 2, and ONUs (Optical Network Units) are used as the terminators 4 is described”), wherein the OTDR is optically connected to N optical fibers (f5/f6, or f7-f9), each having dedicated reflectors (terminators 4a-4f etc. in Figures 1 and 5-7 etc., Abstract, and [0107]-[0113] etc.; e.g., fiber f5 has a reflector/terminator 4a, and fiber f6 has a reflector/terminator 4b. Figure 22, [0237], “the optical fiber lengths from the measurement apparatus 350 to the respective ONUs 420-1 to 420-N as the terminators are previously designed to be different when the optical fibers are deployed.”) connected to an end (Figures 1 and 5-7, terminator. Figure 22, the ONU) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (Abstract, and [0117]-[0122] etc., “In the normal information recording portion 14b, information with regard to intensities of the reflected lights which, after being emitted from the test apparatus 2 via the splitters 3, are reflected and returned by the respective terminators 4 is previously recorded. The intensities of the reflected lights recorded in this normal information recording portion 14b are those from the respective terminators 4 in the case where there is no failure in the optical lines f (f1 to f10)”, and “The attenuation amount determination portion 15 determines by how much the reflected light intensity of the predetermined terminator 4 previously recorded in the normal information recording portion 14b is attenuated from the corresponding reflected light intensity recorded in the monitored information recording portion 14c. Furthermore, the attenuation amount determination portion 15 determines whether or not the attenuated amount is equal in value to the attenuated amount of the other terminators 4 belonging to the same group”. And Figure 3, “one example of group information recorded in the group information recording portion 14a. As shown in the figure, information with regard to the terminators 4 connected to the same splitter 3 is recorded as group information, classified for every group. For example, the terminators 4a, 4b connected to the splitter 3b are recorded as in group g1”. That is, the “normal information” is used as a reference for determining an attenuation for each optical fibers, and the “normal information” can be viewed as a “calibrated” reflective signal), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”), wherein the OTDR is a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a forms a multi-channel OTDR, which has three parallel inputs/outputs associated with fibers f2, f3 and f4), having multiple parallel inputs/outputs (e.g., the three parallel inputs/outputs for the fibers f2-f4) each coupled through a dedicated optical fiber (one of the f2, f3, or f4) to one of a plurality of 1 x N independent splitters (splitters 3b-3d in Figure 1 etc.),
a 1 x N optical splitter (e.g., the splitter 3b in Figure 1, or 410 in Figure 22) that is optically connected to the OTDR (Figures 1 and 22 etc.) to test at least one optical fiber of N optical fibers that are optically connected to the 1x N optical splitter (Figures 4, 11-12 and 16 etc.; and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”), wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., the splitter 3b), wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate ([0110], “As a splitter 3, for example a PLC (Planar Lightwave Circuit) type splitter can be used in which optical waveguides are branched in a tree-like manner on a silica substrate”, and [0184]) to implement a plurality of splitting ratios (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (e.g., the splitter 3b has two test port optical fiber outputs) for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 1 and 5-7 etc. and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”),
wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”).
Nakajima et al does not use the word “calibrated” to label the “normal information”; however, as discussed above, the “normal information” is used as a reference for determining an attenuation for each optical fibers; therefore the “normal information” is a type of “calibrated” reflective signal. Another prior art, Daems, also discloses a system/method for “ABSOLUTE OPTICAL ATTENUATION MEASUREMENT WITH OTDR” (title), and “Devices and methods for optical measurements in point-to-point and point-to-multipoint networks, e.g. like PON networks with splitters are described in which reflected power from some known reflections at the end of the lines is used to determine the attenuation and stability of the attenuation of each line” (Abstract). As shown in Figures 2 and 4 etc., reflectors (14 and 16 in Figure 2, or Ref R1 and Ref R2 in Figure 4; [0042]-[0045] and [0059] etc.) are implemented at the end of fibers, and “FIG. 4 shows how test equipment in accordance with the present invention can be calibrated” ([0029]) and “This calibration can be done when setting up the optical network. Once calibrated, the measurement of absolute loss can be done without further use of power meters” ([0059]); and “Accurate loss measurements are possible from just one side of the network through the splitter” ([0064]); and “It can be understood from the above that the measured absolute values of loss are obtained by methods and devices according to the present invention. As an extension of the present invention, the network can be monitored over time and changes in loss can be detected, e.g. as caused by a sharp bend introduced into a fiber. The measurement of absolute loss allows a change over time to be detected, whereas relative methods may suffer from changes in conditions between measurements which alter the result”; therefore, Daems teaches/suggests “dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”. In Figures 2 and 4, Daems uses the power level of the signal reflected from the retuning device 10 as a reference to calculate the “absolute loss” of each branch ([0049]-[0059]); and in Minami’s Figures 2 and 5, the power level of the signal reflected from the coupler CP1 is used as a reference to evaluate the signal levels/loss/attenuations of different fiber paths (Figure 2, at Distance 0 “CP1”, the power is normalized to “1”, or P/P0 is 1; and all other signal levels reflected from different paths/points are relative to or compared with the power level “1” reflected by CP1); then, the scheme or processes used for calculate a value representative of the absolute loss of each branch also can be applied to the system of Nakajima et al.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Daems to the system/method of Nakajima et al so that accurate calibrated reflective signals for use as a reference for determining an attenuation for each optical fiber can be obtained, and fault events and position at faults can be accurately identified.
5). With regard to claim 17, Nakajima et al and Daems disclose all of the subject matter as applied to claim 16 above. And the combination of Nakajima et al and Daems further discloses wherein the OTDR is optically connected to the N optical fibers to extract, from each optical fiber of the N optical fibers, information by analyzing signals returned from the N optical fibers (Minami: Figures 2-6 etc. Nakajima: Figures 4, 11-12 and 16 etc., [0117]-[0122] etc.).
6). With regard to claim 18, Nakajima et al and Daems disclose all of the subject matter as applied to claim 16 above. And the combination of Nakajima et al and Daems further discloses wherein the OTDR is optically connected to N optical fibers including the optical fiber to compare, for the N optical fibers, N simultaneous test results to a reference test result to identify changes on at least one optical fiber under test of the N optical fibers (Nakajima: Figures 1, 4-7, 11-12 and 16 etc.; [0117]-[0122] and [0127] etc.).
7). With regard to claim 22, Nakajima et al and Daems disclose all of the subject matter as applied to claim 16 above. And the combination of Nakajima et al and Daems further discloses wherein the OTDR operates at a different wavelength than a traffic wavelength (Nakajima: [0239], “The directional coupler 400 performs multiplexing/demultiplexing with wavelength dependency to multiplex communication light incident from the transmission apparatus 390 via the optical fiber 330 and an optical pulse from the measurement apparatus 350 which is incident from the optical switch 340 via the optical fiber 500-1, and outputs the multiplexed communication light and optical pulse to the optical fiber 360”; that is, the OTDR operates at a different wavelength than a traffic wavelength).
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Nakajima et al and Daems as applied to claim 1 above, and in further view of Perry (US 2023/0013084).
Nakajima et al and Daems disclose all of the subject matter as applied to claim 1 above. But, Nakajima et al and Daems do not expressly disclose the optical fiber monitoring apparatus according to claim 1, further comprising: N optical fibers of different lengths optically inserted between the N test port optical fiber outputs and N optical fibers including the optical fiber, wherein the N optical fibers are optically connected to the N test port optical fiber outputs.
However, to introduce N delay fibers into the transmission paths for OTDR is a common practice. E.g., Perry discloses a system/method to monitor optical fibers. As shown in Figure 2F, 4 optical fibers of different lengths (287a-287d) optically inserted between a N test port optical fiber outputs (splitter multi ports) and N optical fibers (284a-284d) including the optical fiber (284), wherein the N optical fibers are optically connected to the N test port optical fiber outputs (Figure 2F).
It is also worth to point out that Perry also discloses that dedicated reflectors are implemented at the end of each fiber (Figure 1: at the End Equip 207; Figure 2F: the terminating connectors 289); “installation and/or maintenance teams dispatched to the field for installation and/or maintenance may conduct supplemental OTDR measurements on the entire PON 211 and/or segments of the PON 211, such as the first optical fiber 202 and/or the distal optical fibers 206. Results, including cable lengths, may be stored and/or otherwise retained in PON configuration records. Similarly, the timing offsets of the output ports 205 of the splitter 203 may be measured and/or otherwise determined according to specification sheets, calibration records, manufacturing records, and the like” ([0059]); “the timing offset values may be determined at a time of manufacture, e.g., curing a characterization or performance test and/or calibration procedure.” ([0075]); “It is understood that a device characterization and/or calibration procedure by which the delay values are determined may be performed at a time of manufacture and/or at a time of installation or perhaps even post installation. For example, a test pulse may be injected into the input, e.g., port 0, and divided into four pulse signal segments, one at each of the output ports, e.g., ports 1-4. A time difference may be measured and/or otherwise calculated based on measured time differences between injection of the input test pulse and detective of the respective output test pulses. The resulting delay measurements may be recorded and/or otherwise noted, e.g., in association with the particular optical splitter device serial number, to the extent the results may vary from device to device” ([0090]); as shown in Figure 2B, “The example OTDR trace 227 represents a graphical signature of an optical fiber network, e.g., PON 211 (FIG. 2A). The trace 227 indicates attenuation along a length of the optical fiber, which provides insight into the performance of the link components (cable, connectors, and splices) and the quality of an installation by examining non-uniformities in the OTDR trace 220” ([0053]-[0054]); and “According to the illustrative PON 211, the fourth, fifth and sixth events 223d, 223e, 223f correspond to fiber terminations at the ONTs 207” ([0058]); and then Figure 2C shows “The example trace 237 is presented as a graph with magnitude along a vertical axis 231 and time along a horizontal axis 232. In particular, the trace 237 represents a trace obtained from the same PON 211, to permit a comparison to the initial trace 227 (FIG. 2B) obtained during normal operating conditions, e.g., at a time of installation and/or reconfiguration. Any changes to the PON 211 that may result from breaks, bends, stretches and/or configuration changes, are observable as differences between the initial trace 227 and the example subsequent trace 237” ([0063]); therefore, Figure 2B of Perry is also “calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”; as shown in Figure 2C, the original event 233e “does not appear in the subsequent trace 237”, instead a new event 236 comes.
As disclosed by Perry, “The optical delay devices provide distinguishable delay values, that delay the divided portions of the optical signal, the distinguishable delay values facilitating associations of the PON segments to the output ports based on optical time domain reflectometry (OTDR) measurements obtained via the input port” (Abstract, and [0089]-[0096]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use fiber delays as taught by Perry to the system/method of Nakajima et al and Daems so that distinguishable delay values/events can be obtained and identified, and coincidence of reflected pulses from different fibers under test can be avoided.
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Nakajima et al and Daems as applied to claim 1 above, and in further view of Perry (US 2023/0013084) and Martel et al (US 2020/0252125).
Nakajima et al and Daems discloses all of the subject matter as applied to claim 1 above. And Nakajima et al and Daems disclose wherein the N optical fibers are optically connected to the N test port optical fiber outputs (Nakajima: Figures 1, 5-7 and 22).
But, Nakajima et al and Daems do not expressly disclose the optical fiber monitoring apparatus according to claim 1, further comprising: N antennas connected to N optical fibers including the optical fiber.
However, it is obvious to one skilled in the art that the system/method disclosed by Nakajima et al and Daems can be used for Radio-over-Fiber (RoF) system/method, in which antennas are connected to optical fibers, respectively. E.g., Perry discloses a multi-path OTDR system (Figure 2A) functioning within the communication network of Figure 1 ([0007] and [0039]); and Figure 1 can be the distributed antennas networks ([0161], “the distributed antennas networks shown in FIG. 1(s) that enhance wireless service coverage by providing more network coverage”, and [0035]), and the end equipment can be antennas (e.g., 122 in Figure 1). Another prior art, Martel et al, also discloses a system/method in which N antennas connected to N optical fibers (Figure 1, and [0024]-[0028] etc., “send an optical probe signal to the particular RRH 12, 14, 16 and receive a back-reflected signal to perform fiber monitoring testing (e.g., OTDR)”, the RRH 12/14/16 are remote radio head, or antenna).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Perry and Martel et al to the system/method of Nakajima et al and Daems so that the OTDR can be used to monitor the radio-over-fiber system.
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Nakajima et al and Daems as applied to claim 1 above, and further in view of Smith et al (US 2013/0259469) and Kim et al (US 2011/0026923).
Nakajima et al and Daems disclose all of the subject matter as applied to claim 1 above. But, Nakajima et al and Daems do not expressly disclose wherein the OTDR is a multi-wavelength OTDR, further comprising: a multi-wavelength multiplexer/demultiplexer optically inserted between the OTDR and the plurality of 1 x N independent splitters.
However, an OTDR that outputs a plurality of wavelength is known in the art. E.g., Smith et al discloses a system/method to monitor a passive optical network (PON). As shown in Figures 4-6, an OTDR can send multiple wavelengths; and a multi-wavelength multiplexer/demultiplexer (e.g., 510) can be used to demultiplex the output from the OTDR and multiplex reflected signals from the fibers under test. In Figure 5, Smith et al does not expressly show a plurality of splitters connected to the output ports of the multiplexer/demultiplexer (e.g., 510/515). However, fist, Nakajima et al discloses that a splitter (e.g., 3a in Figure 1) can be inserted between the OTDR (1a) and a plurality of 1 x N splitters (3b-3d). Second, another prior art, Kim et al, discloses a WDM-TDM-PON (Figures 2 and 23 etc.), as shown in Figures 2 and 23, optical splitters (205 in Figure 2, or the 1:M splitters in Figure 23) are connected to a multi-wavelength multiplexer/demultiplexer (Muc/Demux). By using the WDM-TDM structure with splitters, the optical line terminal (OLT) can reach more ONUs or clients grouped by splitters. And Kim et al also discloses that a monitoring structure similar to the OTDR can be installed in the OLT (Figures 27 and 29), as shown in Figure 29, a plurality of wavelengths are outputs from the multiplexer 2665 and sent downstream for monitoring fibers.
By using different wavelengths and each splitter associating with one wavelength, reflected pulses on different wavelengths, which arrive the detector at the same time, are distinguishable due to their different wavelengths. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Smith et al and Kim et al to the system/method of Nakajima et al and Daems so that a multiplexer/demultiplexer, instead of a splitter, is used between the OTDR and the plurality of 1 x N splitters, and a WDM-TDM OTDR (WDM+Splitters) can be obtained and the functions of the system/method is enhanced.
Claims 9 and 23 are rejected under 35 U.S.C. 103 as being unpatentable over Nakajima et al and Daems as applied to claims 1 and 16 above, and in further view of Lam et al (US 9,240,855).
1). With regard to claim 9, Nakajima et al and Daems discloses all of the subject matter as applied to claim 1 above. And the combination of Nakajima et al and Daems disclose wherein the OTDR operates at a different wavelength than a traffic wavelength (Nakajima: Figure 22, [0239], “The directional coupler 400 performs multiplexing/demultiplexing with wavelength dependency to multiplex communication light incident from the transmission apparatus 390 via the optical fiber 330 and an optical pulse from the measurement apparatus 350 which is incident from the optical switch 340 via the optical fiber 500-1, and outputs the multiplexed communication light and optical pulse to the optical fiber 360”; that is, the OTDR operates at a different wavelength than a traffic wavelength), further comprising: a wavelength dependent multiplexer (e.g., Nakajima: WDM 400 in Figure 22) to insert a test signal on the optical fiber.
But, in Figure 2 of Daems, the wavelength dependent multiplexer (WDM 4) is on the leading fiber (22), not on the fibers (24) after the splitter 12.
However, Lam et al discloses an optical fiber monitoring apparatus (Figures 1-3 and 6); wherein the OTDR operates at a different wavelength (wavelength associated with OTDR 135) than a traffic wavelength (Lam: wavelengths associated with the OLT TX/RX 125; column 4 lines 50-56), further comprising: a wavelength dependent multiplexer (Lam: e.g., wavelength selective 3-port optical couplers 210) to insert a test signal on the optical fiber (145 in Figure 3; or 210 in Figures 2 and 6).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Lam et al to the system/method of Nakajima et al and Daems so that the test/monitoring signals and the data traffic can be properly sent to the desired destination without interference.
2). With regard to claim 23, Nakajima et al and Daems discloses all of the subject matter as applied to claim 16 above. And the combination of Nakajima et al and Daems disclose the optical fiber monitoring apparatus according to claim 16, further comprising a wavelength dependent multiplexer to insert a test signal (e.g., the WDM 4 in Figure 2 of Daems. Nakajima: WDM 400 in Figure 22) to insert a test signal on the optical fiber (Daems: 22).
But, in Figure 2 of Daems, the wavelength dependent multiplexer (WDM 4) is on the leading fiber (22), not on the fibers (24) after the splitter 12.
However, Lam et al discloses an optical fiber monitoring apparatus (Figures 1-3 and 6), and the OTDR operates at a different wavelength (wavelength associated with OTDR 135) than a traffic wavelength (Lam: wavelengths associated with the OLT TX/RX 125; column 4 lines 50-56), and a wavelength dependent multiplexer (Lam: e.g., wavelength selective 3-port optical couplers 210) to insert a test signal on the optical fiber (145 in Figure 3; or 210 in Figures 2 and 6).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Lam et al to the system/method of Nakajima et al and Daems so that the test/monitoring signals and the data traffic can be properly sent to the desired destination without interference.
Claims 10-13 and 15 are rejected under 35 U.S.C. 103 as being unpatentable over Nakajima et al (US 2009/0190921) in view of Chen et al (US 9,435,712) and Daems (US 2011/0268438).
1). With regard to claim 10, Nakajima et al discloses an optical fiber monitoring apparatus (Figures 1 and 22 etc.) comprising:
an OTDR (2 in Figure 1, [0170], “an OTDR (Optical Time Domain Reflectometer) is used as the test apparatus 2, and ONUs (Optical Network Units) are used as the terminators 4 is described”) including an OTDR optical source (the optical source that sends the light to the fiber f1/splitter 3a; [0010], “an OTDR test apparatus (including a light source) 1122 for utilizing backscattering light to measure a loss of the optical fiber and to detect a failure and a location of failure”), wherein the OTDR is optically connected to N optical fibers (f5-f6, or f7-f9), each having dedicated reflectors terminators 4a-4f etc. in Figures 1 and 5-7 etc., Abstract, and [0107]-[0113] etc.; e.g., fiber f5 has a reflector/terminator 4a, and fiber f6 has a reflector/terminator 4b. Figure 22, [0237], “the optical fiber lengths from the measurement apparatus 350 to the respective ONUs 420-1 to 420-N as the terminators are previously designed to be different when the optical fibers are deployed.”) connected to an end (Figures 1 and 5-7, terminator. Figure 22, the ONU) to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers (Abstract, and [0117]-[0122] etc., “In the normal information recording portion 14b, information with regard to intensities of the reflected lights which, after being emitted from the test apparatus 2 via the splitters 3, are reflected and returned by the respective terminators 4 is previously recorded. The intensities of the reflected lights recorded in this normal information recording portion 14b are those from the respective terminators 4 in the case where there is no failure in the optical lines f (f1 to f10)”, and “The attenuation amount determination portion 15 determines by how much the reflected light intensity of the predetermined terminator 4 previously recorded in the normal information recording portion 14b is attenuated from the corresponding reflected light intensity recorded in the monitored information recording portion 14c. Furthermore, the attenuation amount determination portion 15 determines whether or not the attenuated amount is equal in value to the attenuated amount of the other terminators 4 belonging to the same group”. And Figure 3, “one example of group information recorded in the group information recording portion 14a. As shown in the figure, information with regard to the terminators 4 connected to the same splitter 3 is recorded as group information, classified for every group. For example, the terminators 4a, 4b connected to the splitter 3b are recorded as in group g1”. That is, the “normal information” is used as a reference for determining an attenuation for each optical fibers, and the “normal information” can be viewed as a “calibrated” reflective signal), wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”), and
wherein the OTDR is a simultaneous multi-channel OTDR (e.g., the combination of enclosure 1a and splitter 3a forms a multi-channel OTDR, which has three parallel inputs/outputs associated with fibers f2, f3 and f4) having multiple, parallel inputs/outputs (e.g., the three parallel inputs/outputs for the fibers f2-f4) each coupled through a dedicated optical fiber to one of a plurality of 1 x N independent splitters (3b-3d in Figure 1 etc.);
an OTDR optical receiver ([0109], “The test apparatus 2 emits an optical signal to the splitter 3a and receives an optical signal emitted by the splitter 3a via the optical line f1 based on the control by the optical line monitoring apparatus 1”, it is inherent that an OTDR optical receiver is in the test apparatus 2); and
wherein the plurality of 1 x N independent splitters includes the 1 x N optical splitter (e.g., the splitter 3b), wherein the 1 x N optical splitter utilizes a planar lightwave circuit (PLC) having a waveguide on a silica glass substrate ([0110], “As a splitter 3, for example a PLC (Planar Lightwave Circuit) type splitter can be used in which optical waveguides are branched in a tree-like manner on a silica substrate”, and [0184]) to implement a plurality of splitting ratios (Figure 1 etc., splitting ratio can be 1:2 or 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”);
wherein N is greater than one (Figure 1 etc., splitting ratio can be 1:2 and 1:3 etc.; Figure 22, [0235]-[0238], “The number of branches in a general splitter is 4, 8, 16, and 32. It is possible to provide more branches by connecting splitters in a multistage”),
wherein the 1 x N optical splitter includes N test port optical fiber outputs (e.g., the splitter 3b has two test port optical fiber outputs), and
wherein each test port optical fiber output is optically connectable to an optical fiber (e.g., the two test ports of the splitter 3b is optically connectable to two optical fibers f5 and f6, respectively) to optically connect the optical fiber to the OTDR optical source and the OTDR optical receiver for simultaneous monitoring of each test port optical fiber output by the OTDR (Figures 1 and 5-7 etc. and [0127] etc., “The optical signal emitted from the test apparatus 2 is branched by the respective splitters 3 laid in a tree-like manner, and reflected by the respective terminators 4 to be returned to the test apparatus 2. The test apparatus connection portion 13 acquires information with regard to a waveform of the multiplexed reflected lights incident in the test apparatus 2, and the control portion 12 records the information with regard to the waveform of the multiplexed reflected lights in the monitored information recording portion 14c (Step S04)”).
Nakajima et al does not use the word “calibrated” to label the “normal information”, and in Figures 1 and 22 etc., Nakajima et al does not expressly show the detail inside the OTDR, or Nakajima et al does not expressly disclose: an optical coupler optically inserted between the OTDR optical source and the OTDR optical receiver, and the 1 x N optical splitter.
Regarding the optical coupler and optical source and receiver etc., however, to implement a coupler in the OTDR so that one port is used to send a test signal out and receive reflected signal is well known in the art. E.g., Chen et al discloses an optical transmission system/method with OTDR, as shown in Figure 3, the OTDR includes an optical coupler (340) optically inserted between the OTDR optical source (310/320), the OTDR optical receiver (330), and an 1 x N optical splitter (120 in Figure 1).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use a coupler as taught by Chen et al to the OTDR of Nakajima et al so that the test signal can be conveniently sent to a splitter and reflected signals can be properly directed to a detector/receiver via a common port of the coupler.
Nakajima et al does not use the word “calibrated” to label the “normal information”; however, as discussed above, the “normal information” is used as a reference for determining an attenuation for each optical fibers; therefore the “normal information” is a type of “calibrated” reflective signal. Another prior art, Daems, also discloses a system/method for “ABSOLUTE OPTICAL ATTENUATION MEASUREMENT WITH OTDR” (title), and “Devices and methods for optical measurements in point-to-point and point-to-multipoint networks, e.g. like PON networks with splitters are described in which reflected power from some known reflections at the end of the lines is used to determine the attenuation and stability of the attenuation of each line” (Abstract). As shown in Figures 2 and 4 etc., reflectors (14 and 16 in Figure 2, or Ref R1 and Ref R2 in Figure 4; [0042]-[0045] and [0059] etc.) are implemented at the end of fibers, and “FIG. 4 shows how test equipment in accordance with the present invention can be calibrated” ([0029]) and “This calibration can be done when setting up the optical network. Once calibrated, the measurement of absolute loss can be done without further use of power meters” ([0059]); and “Accurate loss measurements are possible from just one side of the network through the splitter” ([0064]); and “It can be understood from the above that the measured absolute values of loss are obtained by methods and devices according to the present invention. As an extension of the present invention, the network can be monitored over time and changes in loss can be detected, e.g. as caused by a sharp bend introduced into a fiber. The measurement of absolute loss allows a change over time to be detected, whereas relative methods may suffer from changes in conditions between measurements which alter the result”; therefore, Daems teaches/suggests “dedicated reflectors connected to an end to generate calibrated reflective signals for use as a reference for determining an attenuation for each of the N optical fibers”. In Figures 2 and 4, Daems uses the power level of the signal reflected from the retuning device 10 as a reference to calculate the “absolute loss” of each branch ([0049]-[0059]); and in Minami’s Figures 2 and 5, the power level of the signal reflected from the coupler CP1 is used as a reference to evaluate the signal levels/loss/attenuations of different fiber paths (Figure 2, at Distance 0 “CP1”, the power is normalized to “1”, or P/P0 is 1; and all other signal levels reflected from different paths/points are relative to or compared with the power level “1” reflected by CP1); then, the scheme or processes used for calculate a value representative of the absolute loss of each branch also can be applied to the system of combined Smith et al and Minami et al.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Daems to the system/method of Nakajima et al and Chen et al so that accurate calibrated reflective signals for use as a reference for determining an attenuation for each optical fiber can be obtained, and fault events and position at faults can be accurately identified.
2). With regard to claim 11, Nakajima et al and Chen et al and Daems disclose all of the subject matter as applied to claim 10 above. And the combination of Nakajima et al and Chen et al Daefurther discloses wherein the OTDR optical source includes a laser (e.g., laser 310 in Chen).
3). With regard to claim 12, Nakajima et al and Chen et al and Daems disclose all of the subject matter as applied to claim 10 above. And the combination of Nakajima et al and Chen et al Daems further discloses wherein the OTDR optical receiver includes a photodiode (e.g., 330 in Chen).
4). With regard to claim 13, Nakajima et al and Chen et al and Daems disclose all of the subject matter as applied to claim 10 above. And the combination of Nakajima et al and Chen et al Daems further discloses wherein the optical coupler is an M-port optical coupler (e.g., 3-port optical coupler 340 in Chen).
5). With regard to claim 15, Nakajima et al and Chen et al and Daems disclose all of the subject matter as applied to claims 10 and 13 above. And the combination of Nakajima et al and Chen et al and Daems further discloses wherein M is equal to three (Chen: 3-port coupler 340).
Claim 14 is rejected under 35 U.S.C. 103 as being unpatentable over Nakajima et al and Chen et al Daems as applied to claims 10 and 13 above, and in further view of Husbands (US 4,449,043).
Nakajima et al and Chen et al Daems discloses all of the subject matter as applied to claims 10 and 13 above. But, Nakajima et al and Chen et al Daems do not expressly disclose wherein the optical coupler includes an additional output connected to an additional measurement port.
However, to add additional port to a coupler for additional purpose is known in the art. E.g., Husbands discloses a system/method to monitor fiber connections etc. As shown in Figure 1, instead of a 3-port coupler, a 4-port coupler is used: port 28 for light source, port 30 for receiving reflected signals, port 34 for transmission/receiving (common port), an additional output (B) connected to an additional measurement port (32, for monitoring the output signals).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Husbands to the system/method of Nakajima et al and Chen et al and Daems so that additional port can be used for additional/auxiliary purpose to enhance the function of the system/method.
Claims 24-25 are rejected under 35 U.S.C. 103 as being unpatentable over Nakajima et al and Daems as applied to claims 1 and 16 above, and in further view of Chen et al (US 9,435,712).
Nakajima et al and Daems disclose all of the subject matter as applied to claims 1 and 16 above. And the combination of Nakajima et al and Daems further discloses the optical fiber monitoring apparatus according to claims 1 and 16, further comprising a receiver (because it is an OTDR, it is inherent that a receiver is in the OTDR so to detect the reflected signals. Nakajima: [0109], “The test apparatus 2 emits an optical signal to the splitter 3a and receives an optical signal emitted by the splitter 3a via the optical line f1 based on the control by the optical line monitoring apparatus 1”, it is inherent that an OTDR optical receiver is in the test apparatus 2).
But, Nakajima et al and Daems do not expressly show the detail inside the OTDR, or Nakajima et al and Daems do not expressly show a photodiode is in the receiver.
However, Chen et al discloses an optical transmission system/method with OTDR, as shown in Figure 3, the OTDR includes an optical coupler (340) optically inserted between the OTDR optical source (310/320), the OTDR optical receiver (330), and an 1 x N optical splitter (120 in Figure 1). And the OTDR optical receiver includes a photodiode (e.g., 330).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Chen et al to the OTDR of Nakajima et al and Daems so that the reflected test/monitoring signal can be properly detected.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
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/LI LIU/Primary Examiner, Art Unit 2634 January 18, 2026