DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 12/12/2025 has been entered, based on the after-final filing of 11/17/2025.
Response to Arguments
Rejection under 35 U.S.C. § 112(b)
The rejection under 35 U.S.C. § 112(b) is overcome by amendment.
Rejections under 35 U.S.C. § 102
Applicant's first argument is that the claimed invention uses a reference light beam split from the combined light as part of a feedback system, however, this argument is not persuasive. The quote Applicant attributes to claim 13 regarding "a beam splitter" and "a reference light beam" appears to come from claim 1 or claim 16. Claim 13 differs from the other independent claims, for example, in that the combined light is directed into an interferometer (which comprises a first beam splitter and a second beam splitter, but no unnumbered beam splitter) with a frequency response and complementary frequency response, resulting in two output light beams whose intensities are compared for each frequency. Unlike the other independent claims, claim 13 does not recite a "reference light beam" "based on the combined light beam" (quoting Applicant's remarks), even as amended.
Applicant's second argument is that the claimed invention differs from Toba due to the presence of frequency reference light source 31 in FIG. 12, however, this argument is moot. Frequency reference light source 31 is not relied on in this or the previous action and is not required for the embodiment found in FIG. 12 of Toba to match all the limitations of claim 13. Further, the open-ended "comprising" language of the claim does not prohibit the addition of unclaimed components.
Applicant's third argument is that the claimed invention differs from Toba in operating as a feedback loop system, however, this argument is not persuasive. Note in FIG. 12 of Toba that the beams from light sources 121 and 122 (in the upper-left) are sent together through the Mach-Zehnder interferometer (center) to detectors (upper-right). The detectors send signals around the bottom of the figure (lower-right to lower-left) back to elements 111 and 112, which use that signal as feedback to control those same light sources 121 and 122. In other words, Toba does teach generating first and second control signals as feedback sent to the first and second light sources. Also see paragraph 35 of the previous action.
The rejections under 35 U.S.C. § 102 are maintained.
Rejections under 35 U.S.C. § 103
Applicant's first argument is that FIG. 12 of Toba does not teach certain aspects of claims rejected under 35 U.S.C. § 103, however, this argument is moot. The embodiment found in FIG. 12 of Toba is only relied on in this and the previous action with respect to claim 13 and its dependent claims (15 and 23). Prior art rejections of claims 1, 16, and their dependent claims instead rely on the embodiment found in FIG 2 of Toba, as modified by the teachings of Lei and further modified by a different embodiment of Toba, found in FIG. 11.
Examiner believes that the arguments in this section are intended to refer to claim 1 rather than claim 13. If this is not the case, see the responses above.
Applicant's second argument is that claim 1 differs from Toba due to Toba teaching a frequency reference light source 31, while the claimed invention uses a portion of the combined beam as a reference, however, this argument moot. This and the previous action rely on Lei, not Toba, to teach the use of a reference beam based on a combined beam (FIG. 6, fourth fiber 216 of Lei). See paragraphs 60-64 of the previous action and the rejection below.
Applicant's third argument is that claim 1 differs from Toba, as modified by Lei, in forming a feedback loop system, however, this argument is not persuasive. Toba and Lei both use feedback loops in controlling the light sources. For example, see the larger of the curved loops in FIG. 2 of Toba, which is visually suggestive of the path of signals that starts with the first and second light sources and returns to those light sources.
The rejections under 35 U.S.C. § 103 are maintained.
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
Claim(s) 13, 15, and 23 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Toba (Foreign Patent Document JPH09261181A).
Regarding claim 13, Toba teaches a multiple optical frequency monitoring assembly, comprising: a first light source configured to generate a first light beam at a first optical frequency (FIG. 12, semiconductor laser 121, with frequency f1);
a second light source configured to generate a second light beam at a second optical frequency different from the first optical frequency (FIG. 12, semiconductor laser 122, with frequency f2);
combiner optics configured to combine the first light beam and the second light beam to generate a combined light beam (FIG. 12, optical multiplexer 20);
an interferometer (FIG. 12, Mach-Zehnder (MZ) interferometer 33) characterized by an initial frequency response and a complementary frequency response that is in anti-phase with the initial frequency response (FIG. 10, top graph, solid and dotted curves),
wherein the interferometer comprises a first beam splitter and a second beam splitter that are separated by a first path and a second path (inherent to a Mach-Zehnder interferometer, see Paschotta 1 (Non-Patent Literature “Interferometers”), section Mach-Zehnder Interferometer, second sentence),
wherein the first path is configured with a first path length and a second path is configured with a second path length that differs from first path length by a path length difference (see Paschotta 1, section Mach-Zehnder Interferometer, paragraph 1, sentence 3), and
wherein the path length difference defines the free spectral range of the initial frequency response and the complementary frequency response (inherent. See Paschotta 1, section Mach-Zehnder Interferometer, paragraph 1, sentence 4),
wherein the interferometer is configured to receive the combined light beam (from optical coupler 22), generate a first output light beam based on the combined light beam and the initial frequency response (FIG. 12, sent to optical demultiplexer 42), and generate a second output light beam based on the combined light beam and the complementary frequency response (FIG. 12, sent to optical demultiplexer 43),
wherein the first output light beam has first transmitted intensity corresponding to a first portion of the first light beam and a second transmitted intensity corresponding to a first portion of the second light beam (this is typical for a Mach-Zehnder interferometer like that of Toba, as part of each of the inputs exits via the first output. See Paschotta 1, section Mach-Zehnder Interferometer, paragraph 1, sentence 3 and paragraph 2, sentence 1),
wherein the second output light beam has a third transmitted intensity corresponding to a second portion of the first light beam and a fourth transmitted intensity corresponding to a second portion of the second light beam (this is typical for a Mach-Zehnder interferometer like that of Toba, as part of each of the inputs exits via the second output. See Paschotta 1, section Mach-Zehnder Interferometer, paragraph 1, sentence 3 and paragraph 2, sentence 1), and
wherein the first transmitted intensity is based on the first optical frequency and the initial frequency response, the second transmitted intensity is based on the second optical frequency and the initial frequency response, the third transmitted intensity is based on the first optical frequency and the complementary frequency response, and the fourth transmitted intensity is based on the second optical frequency and the complementary frequency response (this is typical for a Mach-Zehnder interferometer like that of Toba when it is used as an optical filter. See Paschotta 1, section Mach-Zehnder Interferometer, paragraph 1, sentence 3 and paragraph 2, sentence 1);
filter optics configured to receive the first output light beam and the second output light beam, separate the first portion of the first light beam having the first transmitted intensity from the first portion of the second light beam having the second transmitted intensity (FIG. 12, optical demultiplexer 42), and separate the second portion of the first light beam having the third transmitted intensity from the second portion of the second light beam having the fourth transmitted intensity (FIG. 12, optical demultiplexer 43);
a detector arranged downstream from the filter optics, wherein the detector is configured to measure the first transmitted intensity (FIG. 12, photodetector 511), the second transmitted intensity (FIG. 12, photodetector 512), the third transmitted intensity (FIG. 12, photodetector 531), and the fourth transmitted intensity (FIG. 12, photodetector 532), generate a first ratio value representative of a first ratio between the first transmitted intensity and the third transmitted intensity (FIG. 12, differential or logarithmic differential amplifier 541), and generate a second ratio value representative of a second ratio between the second transmitted intensity and the fourth transmitted intensity (FIG. 12, differential or logarithmic differential amplifier 541); and
a controller configured to:
tune the first optical frequency of the first light source based on the first ratio value (FIG. 12, element 111, described in the specification as a variable frequency power supply, which is likely to mean a power supply that varies a frequency (of the attached laser), rather than that the power itself has variable frequency), by generating a first control signal that is provided to the first light source (FIG. 12, along the signal path represented by the line connecting element 111 to semiconductor laser 121); and
tune the second optical frequency of the second light source based on the second ratio value (FIG. 12, element 112, described in the specification as a variable frequency power supply, which is likely to mean a power supply that varies a frequency (of the attached laser), rather than that the power itself has variable frequency), by generating a second control signal that is provided to the second light source (FIG. 12, along the signal path represented by the line connecting element 112 to semiconductor laser 122).
Regarding claim 15, Toba teaches the multiple optical frequency monitoring assembly of claim 13 (as described above), wherein the initial frequency response comprises a first plurality of frequency ranges and a first plurality of resonant peak frequencies (FIG. 10, cycles and peaks of one of the dotted curve of the top graph) at which a transmittivity of the interferometer is at a maximum transmission level (an ideal Mach-Zehnder interferometer would always have maximum transmission, but not necessarily evenly split between the two outputs. See Paschotta 1, section Mach-Zehnder Interferometer, paragraph 1, sentence 4),
the complementary frequency response comprises a second plurality of frequency ranges and a second plurality of resonant peak frequencies (FIG. 10, cycles and peaks of the solid curve of the top graph) at which the transmittivity of the interferometer is at the maximum transmission level (an ideal Mach-Zehnder interferometer would always have maximum transmission, but not necessarily evenly split between the two outputs. See Paschotta 1, section Mach-Zehnder Interferometer, paragraph 1, sentence 4), and
wherein the first optical frequency resides in a first frequency range of the first plurality of frequency ranges and the second optical frequency resides in a second frequency range of the first plurality of frequency ranges that is different from the first frequency range (FIG. 10, f1 is within the frequency range close to a different peak of the dotted curve than f2 is, so they are in different frequency ranges, separated by at least the free spectral range of the frequency response.).
Regarding claim 23, Toba teaches the multiple optical frequency monitoring assembly of claim 13 (as described above), wherein the first beam splitter is configured to direct the first beam along the first path and direct the second beam along the second path (FIG. 12, first is upper path, second is lower path), and
wherein the second beam splitter is configured to receive the first beam and the second beam, generate the first output light beam based on a first combination of the first beam and the second beam, and generate the second output light beam based on a second combination of the first beam and the second beam (FIG. 12, outputs from right-hand side of MZ 33).
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.
Claim(s) 1-11, 16-17, and 22 is/are rejected under 35 U.S.C. 103 as being unpatentable over Toba (Foreign Patent document JPH09261181A) in view of Lei (US Patent 8611750).
Regarding claim 1, Toba teaches a multiple optical frequency monitoring assembly, comprising: a first light source configured to generate a first light beam at a first optical frequency (FIG. 2, semiconductor laser 11, operating at frequency f1);
a second light source configured to generate a second light beam at a second optical frequency different from the first optical frequency (FIG. 2, semiconductor laser 12, operating at frequency f2);
combiner optics configured to combine the first light beam and the second light beam to generate a combined light beam (FIG. 2, optical multiplexer 20);
an interferometer configured to receive the monitored light beam having a first incident intensity corresponding to the first portion of the first light beam and a second incident intensity corresponding to the first portion of the second light beam (FIG. 2, optical frequency discriminator 30, described in paragraph 13 as a Fabry–Pérot interferometer among other alternatives),
wherein the interferometer is characterized by a resonant frequency response comprising a plurality of frequency ranges and a plurality of resonant peak frequencies at which a transmittivity of the interferometer is at a maximum transmission level (a Fabry–Pérot interferometer will naturally have a resonant frequency response comprising a plurality of resonant peak frequencies. See Paschotta 2 (Non-Patent Literature “Fabry–Pérot Interferometers”), FIG. 1, which shows a resonant frequency response for a Fabry–Pérot interferometer, which includes resonant transmission peaks. It is trivial to assign a plurality of frequency ranges to a resonant frequency response.),
wherein the first optical frequency resides in a first frequency range of the plurality of frequency ranges and the second optical frequency resides in a second frequency range of the plurality of frequency ranges that is different from the first frequency range,
wherein the interferometer is configured to output the monitored light beam as a monitored output light beam according to the resonant frequency response (FIG. 2, output directed from optical frequency discriminator 30 to optical demultiplexer 40),
wherein the monitored output light beam has first transmitted intensity corresponding to the first portion of the first light beam and a second transmitted intensity corresponding to the first portion of the second light beam (this is typical for a Fabry–Pérot interferometer, such as that of Toba),
wherein the first transmitted intensity is based on the first incident intensity, the first optical frequency, and the resonant frequency response (this is typical for a Fabry–Pérot interferometer, such as that of Toba), and
wherein the second transmitted intensity is based on the second incident intensity, the second optical frequency, and the resonant frequency response (this is typical for a Fabry–Pérot interferometer, such as that of Toba);
filter optics configured to receive, via a first filter of the filter optics, the monitored output light beam, and separate the first portion of the first light beam having the first transmitted intensity from the first portion of the second light beam having the second transmitted intensity (FIG. 2, optical demultiplexer 40);
a detector arranged downstream from the filter optics, wherein the detector is configured to measure the first transmitted intensity (FIG. 2, error detection circuit 51), the second transmitted intensity (FIG. 2, error detection circuit 52); and
a controller configured to:
tune the first optical frequency of the first light source based on the first difference value, by generating a first control signal that is provided to the first light source (FIG. 2, error detection circuit 51, which connects back to light source 11, which connects back to light source 11, along a signal path depicted by the arrow that goes around the edge of the figure from the upper-right section, around the bottom, and back up to the upper-left); and
tune the second optical frequency of the second light source based on the second difference value, by generating a second control signal that is provided to the second light source (FIG. 2, error detection circuit 52, which connects back to light source 12, along a signal path depicted by the arrow that goes around the edge of the figure from the upper-right section, around the bottom, and back up to the upper-left, just inside of the feedback path from error detection circuit 51 to light source 11).
The embodiment in FIG. 2 of Toba does not explicitly teach splitting off a reference beam to be measured without passing it through optical frequency discriminator 30 (i.e., does not explicitly teach a beam splitter configured to split the combined light beam into a monitored light beam, comprising a first portion of the first light beam and a first portion of the second light beam, and a reference light beam, comprising a second portion of the first light beam and a second portion of the second light beam;
that the filter optics are configured further to receive, via a second filter of the filter optics, the reference light beam, and separate the second portion of the first light beam having a first reference intensity from the second portion of the second light beam having a second reference intensity;
that the reference light beam bypasses the interferometer in a path from the beam splitter to the filter optics; nor
that the detector is configured to measure the first reference intensity, and the second reference intensity, generate a first difference value representative of a difference between the first transmitted intensity and the first reference intensity, and generate a second difference value representative of a difference between the second transmitted intensity and the second reference intensity).
In the same field of endeavor of locking multiple wavelengths of multiple light sources to particular wavelengths using a single filter, Lei does teach splitting off a reference beam to be measured without passing the reference beam through the filter. In particular, Lei teaches a beam splitter (FIG. 6, splitter 212) configured to split the combined light beam (FIG. 6, from fiber 211) into a monitored light beam (FIG. 6, fiber 213), comprising a first portion of the first light beam and a first portion of the second light beam, and a reference light beam, comprising a second portion of the first light beam and a second portion of the second light beam (FIG. 6, fiber 216); wherein the reference light beam bypasses the interferometer in a path from the beam splitter to the filter optics (FIG. 6, fiber 216 bypasses interferometer 214, labeled “Filter”); and that the detector is configured to measure the reference intensity (FIG. 6, optical-electrical converter 218). By separately measuring an unfiltered version of the light (light that bypasses filter 214), Lei can monitor the power of the lasers separately from measuring how well they match the desired frequency.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the multiple optical frequency monitoring assembly of Toba with the separate reference channel of Lei to separately monitor the power of the light sources in addition to monitoring their frequencies.
While Lei does not teach a dividing the reference beam prior to detecting it, a different embodiment disclosed by Toba does teach that the filter optics (FIG. 11, arrayed waveguide grating type optical demultiplexer 44) are further configured to receive, via a second filter of the filter optics, the reference light beam (FIG. 11, arrayed waveguide grating type optical demultiplexer 44, via port a1 (also note port b1, which would correspond to the claimed first filter of the filter optics when combined with the embodiment of FIG. 2 and the disclosure of Lei)), and separate the second portion of the first light beam having a first reference intensity (FIG. 11, arrayed waveguide grating type optical demultiplexer, via port b2) from the second portion of the second light beam having a second reference intensity (FIG. 11, arrayed waveguide grating type optical demultiplexer, via port b3); and
that the detector is configured to measure the first transmitted intensity (FIG. 11, detector 511), the second transmitted intensity (FIG. 11, detector 512), the first reference intensity (FIG. 11, detector 531), and the second reference intensity (FIG. 11, detector 532), generate a first difference value representative of a difference between the first transmitted intensity and the first reference intensity (FIG. 11, differential or logarithmic differential amplifier 541), and generate a second difference value representative of a difference between the second transmitted intensity and the second reference intensity (FIG. 11, differential or logarithmic differential amplifier 542). By demultiplexing each of two different signals, Toba is able to contrast them to better find the error in the frequency of each light source in parallel.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the multiple optical frequency monitoring assembly of Toba, as modified by Lei, with aspects of a second embodiment of Toba in order to separately measure the contrast between a reference and a filtered signal for each frequency, thereby finding the error for each light source in parallel.
Regarding claim 2, Toba, as modified by Lei, teaches or renders obvious the multiple optical frequency monitoring assembly of claim 1 (as described above).
Toba further teaches that the controller is configured to tune the first optical frequency of the first light source to drive the first difference value to a first predetermined value (paragraph 20 describes that the error detection circuits are designed to detect optical frequency errors (which cause a difference to depart from the predetermined value of 0) and stabilize the frequency, which would remove the error) , and
wherein the controller is configured to tune the second optical frequency of the second light source to drive the second difference value to a second predetermined value (paragraph 20 describes that the error detection circuits are designed to detect optical frequency errors (which cause a difference to depart from the predetermined value of 0) and stabilize the frequency, which would remove the error).
Regarding claim 3, Toba, as modified by Lei, teaches or renders obvious the multiple optical frequency monitoring assembly of claim 1 (as described above).
Toba further teaches that the controller is configured to tune the first optical frequency of the first light source to drive the first optical frequency to a first target optical frequency that corresponds to a first resonant peak frequency of the first frequency range (paragraph 6, first feedback loop, represented abstractly in FIG. 2 as the larger of the two curved feedback loops), and
wherein the controller is configured to tune the second optical frequency of the second light source to drive the second optical frequency to a second target optical frequency that corresponds to a second resonant peak frequency of the second frequency range (paragraph 6, first feedback loop, represented abstractly in FIG. 2 as the larger of the two curved feedback loops).
Regarding claim 4, Toba, as modified by Lei, teaches or renders obvious the multiple optical frequency monitoring assembly of claim 1 (as described above).
Toba further teaches that the controller is configured to tune the first optical frequency of the first light source to drive a first ratio of the first incident intensity and the first transmitted intensity to a first target value (paragraph 6, first feedback loop, represented abstractly in FIG. 2 as the larger of the two curved feedback loops), and
wherein the controller is configured to tune the second optical frequency of the second light source to drive a second ratio of the second incident intensity and the second transmitted intensity to a second target value (paragraph 6, first feedback loop, represented abstractly in FIG. 2 as the larger of the two curved feedback loops).
Regarding claim 5, Toba, as modified by Lei, teaches or renders obvious the multiple optical frequency monitoring assembly of claim 1 (as described above).
Toba further teaches that the filter optics includes at least one optical frequency filter configured to separate, by optical frequency, the first portion of the first light beam having the first transmitted intensity from the first portion of the second light beam having the second transmitted intensity, and separate, by optical frequency, the second portion of the first light beam having the first reference intensity from the second portion of the second light beam having the second reference intensity (FIG. 2, optical demultiplexer 40 separates its input by frequency (light of frequency f1 exits via port b1, light of frequency f2 exits via port b2, and so on)).
Regarding claim 6, Toba, as modified by Lei, teaches or renders obvious the multiple optical frequency monitoring assembly of claim 1 (as described above).
Toba further teaches that the filter optics includes at least one spatial filter configured to separate the first portion of the first light beam having the first transmitted intensity from the first portion of the second light beam having the second transmitted intensity, and separate the second portion of the first light beam having the first reference intensity from the second portion of the second light beam having the second reference intensity (FIG. 2, the outputs of demultiplexer 40 are spatially separated into spatially separate ports for different initial beams of different frequencies originating from different light sources 11-1n).
Regarding claim 7, Toba, as modified by Lei, teaches or renders obvious the multiple optical frequency monitoring assembly of claim 1 (as described above).
Toba further teaches that each frequency range of the plurality of frequency ranges is defined by a free spectral range of the resonant frequency response (FIG. 2, the optical frequency discriminator 30 can be a Fabry–Pérot interferometer, see paragraph 13. Paschotta 2 (Non-Patent Literature “Fabry–Pérot Interferometers”) points out that a Fabry–Pérot interferometer has a free spectral range. It is trivial to choose frequency ranges based on the free spectral range of the Fabry–Pérot interferometer used by Toba).
Regarding claim 8, Toba, as modified by Lei, teaches or renders obvious the multiple optical frequency monitoring assembly of claim 1 (as described above).
Toba further teaches that each frequency range of the plurality of frequency ranges is defined by a respective pair of minima centered on a respective resonant peak frequency of the plurality of resonant peak frequencies (FIG. 2, the optical frequency discriminator 30 can be a Fabry–Pérot interferometer, see paragraph 13. Paschotta 2 (Non-Patent Literature “Fabry–Pérot Interferometers”) shows that a Fabry–Pérot interferometer has resonant peak frequencies (FIG. 1) separated by minima. It is trivial to choose frequency ranges based on the resonant peak frequencies and minima of the Fabry–Pérot interferometer used by Toba).
Regarding claim 9, Toba, as modified by Lei, teaches or renders obvious the multiple optical frequency monitoring assembly of claim 8 (as described above).
Toba further teaches that each respective pair of minima is separated in frequency by a free spectral range of the resonant frequency response (FIG. 2, the optical frequency discriminator 30 can be a Fabry–Pérot interferometer, see paragraph 13. Paschotta 2 (Non-Patent Literature “Fabry–Pérot Interferometers”) points out that a Fabry–Pérot interferometer has a free spectral range, which is the separation between frequencies of minima (or, equivalently, between maxima) of the transmission. It is trivial to choose frequency ranges based on the free spectral range of the Fabry–Pérot interferometer used by Toba).
Regarding claim 10, Toba, as modified by Lei, teaches or renders obvious the multiple optical frequency monitoring assembly of claim 1 (as described above).
Toba further teaches that each resonant peak frequency of the plurality of resonant peak frequencies corresponds to a different frequency range and is separated from an adjacent resonant peak frequency by a free spectral range (FIG. 2, the optical frequency discriminator 30 can be a Fabry–Pérot interferometer, see paragraph 13. Paschotta 2 (Non-Patent Literature “Fabry–Pérot Interferometers”) points out that a Fabry–Pérot interferometer has a free spectral range, which is the separation between frequencies of peaks (or, equivalently, between minima) of the transmission. It is trivial to choose frequency ranges based on the free spectral range of the Fabry–Pérot interferometer used by Toba).
Regarding claim 11, Toba, as modified by Lei, teaches or renders obvious the multiple optical frequency monitoring assembly of claim 1 (as described above).
Toba further teaches that the interferometer is a Fabry-Pérot interferometer (paragraph 13), a Michelson interferometer, or a Mach-Zehnder interferometer (paragraph 13).
Regarding claim 16, Toba teaches a multi-beam monitoring assembly, comprising: a first light source configured to generate a first light beam with a beam property having a first property value (FIG. 2, semiconductor laser 11, operating at frequency f1);
a second light source configured to generate a second light beam with the beam property having a second property value different from the first property value (FIG. 2, semiconductor laser 12, operating at frequency f2);
combiner optics configured to combine the first light beam and the second light beam to generate a combined light beam (FIG. 2, optical multiplexer 20);
an interferometer configured to receive the monitored light beam having a first incident intensity corresponding to the first portion of the first light beam and a second incident intensity corresponding to the first portion of the second light beam (FIG. 2, optical frequency discriminator 30, described in paragraph 13 as a Fabry–Pérot interferometer among other alternatives),
wherein the interferometer is characterized by a resonant frequency response comprising a plurality of frequency ranges and a plurality of resonant peak frequencies at which a transmittivity of the interferometer is at a maximum transmission level (a Fabry–Pérot interferometer will naturally have a resonant frequency response comprising a plurality of resonant peak frequencies. See Paschotta 2 (Non-Patent Literature “Fabry–Pérot Interferometers”), FIG. 1, which shows a resonant frequency response for a Fabry–Pérot interferometer, which includes resonant transmission peaks. It is trivial to assign a plurality of frequency ranges to a resonant frequency response.),
wherein the interferometer is configured to output the monitored light beam as a monitored output light beam according to the resonant frequency response (FIG. 2, output directed from optical frequency discriminator 30 to optical demultiplexer 40),
wherein the monitored output light beam has first transmitted intensity corresponding to the first portion of the first light beam and a second transmitted intensity corresponding to the first portion of the second light beam (this is typical for a Fabry–Pérot interferometer, such as that of Toba),
wherein the first transmitted intensity is based on the first incident intensity, the first property value, and the resonant frequency response (this is typical for a Fabry–Pérot interferometer, such as that of Toba),
wherein the second transmitted intensity is based on the second incident intensity, the second property value, and the resonant frequency response (this is typical for a Fabry –Pérot interferometer, such as that of Toba);
filter optics configured to receive, via a first filter of the filter optics, the monitored output light beam, and separate the first portion of the first light beam having the first transmitted intensity from the first portion of the second light beam having the second transmitted intensity (FIG. 2, optical demultiplexer 40),
a detector arranged downstream from the filter optics, wherein the detector is configured to measure the first transmitted intensity (FIG. 2, error detection circuit 51), the second transmitted intensity (FIG. 2, error detection circuit 52); and
a controller configured to: tune the first property value of the first light source based on the first difference value, by generating a first control signal that is provided to the first light source (FIG. 2, error detection circuit 51, which connects back to light source 11, which connects back to light source 11, along a signal path depicted by the arrow that goes around the edge of the figure from the upper-right section, around the bottom, and back up to the upper-left); and
tune the second property value of the second light source based on the second difference value, by generating a second control signal that is provided to the second light source (FIG. 2, error detection circuit 52, which connects back to light source 12, along a signal path depicted by the arrow that goes around the edge of the figure from the upper-right section, around the bottom, and back up to the upper-left, just inside of the feedback path from error detection circuit 51 to light source 11).
The embodiment in FIG. 2 of Toba does not explicitly teach splitting off a reference beam to be measured without passing it through optical frequency discriminator 30 (i.e., does not explicitly teach a beam splitter configured to split the combined light beam into a monitored light beam, comprising a first portion of the first light beam and a first portion of the second light beam, and a reference light beam, comprising a second portion of the first light beam and a second portion of the second light beam;
that the filter optics are further configured to receive, via a second filter of the filter optics, the reference light beam, and separate the second portion of the first light beam having a first reference intensity from the second portion of the second light beam having a second reference intensity;
that the reference light beam bypasses the interferometer in a path from the beam splitter to the filter optics; nor
that the detector is configured to measure the first reference intensity, and the second reference intensity, generate a first difference value representative of a difference between the first transmitted intensity and the first reference intensity, and generate a second difference value representative of a difference between the second transmitted intensity and the second reference intensity).
In the same field of endeavor of locking multiple beams from multiple light sources to particular property values using a single filter, Lei does teach splitting off a reference beam to be measured without passing the reference beam through the filter. In particular, Lei teaches a beam splitter (FIG. 6, splitter 212) configured to split the combined light beam (FIG. 6, from fiber 211) into a monitored light beam (FIG. 6, fiber 213), comprising a first portion of the first light beam and a first portion of the second light beam, and a reference light beam, comprising a second portion of the first light beam and a second portion of the second light beam (FIG. 6, fiber 216); wherein the reference light beam bypasses the interferometer in a path from the beam splitter to the filter optics (FIG. 6, fiber 216 bypasses interferometer 214, labeled “Filter”); and that the detector is configured to measure the reference intensity (FIG. 6, optical-electrical converter 218). By separately measuring an unfiltered version of the light (light that bypasses filter 214), Lei can monitor the power of the lasers separately from measuring how well they match the desired property value.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the multi-beam monitoring assembly of Toba with the separate reference channel of Lei to separately monitor the power of the light sources in addition to monitoring their property values.
While Lei does not teach a dividing the reference beam prior to detecting it, a different embodiment disclosed by Toba does teach that the filter optics (FIG. 11, arrayed waveguide grating type optical demultiplexer 44) are further configured to receive, via a second filter of the filter optics, the reference light beam (FIG. 11, arrayed waveguide grating type optical demultiplexer 44, via port a1 (also note port b1, which would correspond to the claimed first filter of the filter optics when combined with the embodiment of FIG. 2 and the disclosure of Lei)), and separate the second portion of the first light beam having a first reference intensity (FIG. 11, arrayed waveguide grating type optical demultiplexer, via port b2) from the second portion of the second light beam having a second reference intensity (FIG. 11, arrayed waveguide grating type optical demultiplexer, via port b3); and
that the detector is configured to measure the first transmitted intensity (FIG. 11, detector 511), the second transmitted intensity (FIG. 11, detector 512), the first reference intensity (FIG. 11, detector 531), and the second reference intensity (FIG. 11, detector 532), generate a first difference value representative of a difference between the first transmitted intensity and the first reference intensity (FIG. 11, differential or logarithmic differential amplifier 541), and generate a second difference value representative of a difference between the second transmitted intensity and the second reference intensity (FIG. 11, differential or logarithmic differential amplifier 542). By demultiplexing each of two different signals, Toba is able to contrast them to better find the error in the property value of each light source in parallel.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the multi-beam monitoring assembly of Toba, as modified by Lei, with aspects of a second embodiment of Toba in order to separately measure the contrast between a reference and a filtered signal for each property value, thereby finding the error for each light source in parallel.
Regarding claim 17, Toba, as modified by Lei, teaches or renders obvious the multi-beam monitoring assembly of claim 16 (as described above).
Toba further teaches that the beam property is an optical frequency (paragraph 1).
Regarding claim 22, Toba, as modified by Lei, teaches or renders obvious the multi-beam monitoring assembly of claim 1 (as described above).
Toba further teaches that the configuration of the multiple optical frequency monitoring assembly enables a system that provides a feedback loop with use of the first control signal and the second control signal (FIG. 2 shows a first feedback loop as a curved arrow from the area near the light sources, through the interferometer, demultiplexer, detectors, and back around to the light sources. The closed nature of the loop signifies that it provides a feedback loop. The first and second control signals are on the part of the feedback loop connecting the error detection circuits 51 and 52 back to light sources 11 and 12).
Claim(s) 18-20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Toba (Foreign Patent document JPH09261181A) in view of Lei (US Patent 8611750) and Badraoui (Non-Patent Literature “Enhancing capacity of optical links using polarization multiplexing”).
Regarding claim 18, Toba, as modified by Lei, teaches or renders obvious the multi-beam monitoring assembly of claim 16 (as described above).
Toba does not explicitly teach that the beam property is a linear polarization.
In the same field of endeavor of fiber-optic telecommunication enhancement, Badraoui does teach that the beam property is a linear polarization (introduction, paragraph 1). By applying polarization multiplexing, Badraoui doubles bandwidth efficiency in a way that requires keeping track of the polarization states of the signals.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the multi-beam monitoring assembly of Toba, as modified by Lei and additional teachings of Toba, with the polarization multiplexing of Badraoui and with monitoring the polarization state of the light beams as the beam property under test.
Regarding claim 19, Toba, as modified by Lei and Badraoui, teaches or renders obvious the multi-beam monitoring assembly of claim 18 (as described above).
Toba does not explicitly teach that the first light beam and the second light beam have a same optical frequency.
In the same field of endeavor of fiber-optic telecommunication enhancement, Badraoui does teach that the first light beam and the second light beam have a same optical frequency (section 4, paragraph 1, using a wavelength 1553 nm for both signals implies the same optical frequency for both signals). By using two signals at the same frequency, polarization multiplexing allows twice as many signals in the same bandwidth.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the multi-beam monitoring assembly of Toba, as modified by Lei, additional teachings of Toba, and Badraoui, with the single optical frequency of Badraoui to double the bandwidth efficiency of the system under test.
Regarding claim 20, Toba, as modified by Lei and Badraoui, teaches or renders obvious the multi-beam monitoring assembly of claim 18 (as described above).
Toba does not explicitly teach that the first property value corresponds to a first linear polarization and the second property value corresponds to a second linear polarization that is orthogonal to the first linear polarization.
In the same field of endeavor of fiber-optic telecommunication enhancement, Badraoui does teach that the first property value corresponds to a first linear polarization and the second property value corresponds to a second linear polarization that is orthogonal to the first linear polarization (section 4, paragraph 2, X-polarization is a linear polarization, and Y-polarization is a second linear polarization that is orthogonal to X-polarization). Orthogonal linear polarization states have the benefit of being easy to set up and test.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the multi-beam monitoring assembly of Toba, as modified by Lei, additional teachings of Toba, and Badraoui, using two orthogonal linear polarizations in the manner of Badraoui for ease of setting up and testing the polarization states.
Claim(s) 21 is/are rejected under 35 U.S.C. 103 as being unpatentable over Toba (Foreign Patent document JPH09261181A) in view of Lei (US Patent 8611750) and Paschotta 3 (Non-Patent Literature “Space Division Multiplexing”).
Regarding claim 21, Toba, as modified by Lei, teaches or renders obvious the multi-beam monitoring assembly of claim 16 (as described above).
Toba does not explicitly teach that the beam property is a spatial beam property.
In the same field of endeavor of fiber-optic telecommunication enhancement, Paschotta 3 does teach that the beam property is a spatial beam property (paragraph 1). By using spatial beam properties, more information can be multiplexed through an optical fiber.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the multi-beam monitoring assembly of Toba, as modified by Lei and additional teachings of Toba, with the spatial multiplexing of Paschotta 3 to test the quality of the signals in a spatially multiplexed fiber setup.
Conclusion
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/PAUL SCHNASE/Examiner, Art Unit 2877
/TARIFUR R CHOWDHURY/Supervisory Patent Examiner, Art Unit 2877