Detailed Office 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 .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Election/Restriction
Regarding newly submitted claims 108-132:
Newly submitted claims 108-119 are directed to an invention that is independent or distinct from the invention originally claimed; claim 108 (“A method comprising: adding a plurality of summands using a distributed pulse-amplitude modulation (PAM) aggregation process …”);
Newly submitted claims 120-130 are directed to an invention that is independent or distinct from the invention originally claimed; claim 120 (“A method comprising: performing a multiplication of a matrix and a vector comprising performing addition of multi-bit summands, each multi-bit summand including N bits; wherein first bits of the summands represent a result of a multiplication between a first row of the matrix and the vector…”);
Newly submitted claim 131 is directed to an invention that is independent or distinct from the invention originally claimed; claim 131 (“A method comprising: performing a multiplication of a matrix and a vector comprising performing addition of multi-bit summands …”);
Newly submitted claim 131 is directed to an invention that is independent or distinct from the invention originally claimed; claim 132 (“A computer-readable medium storing instructions that when executed by an optoelectronic computing platform cause the optoelectronic computing platform to perform: …”).
In comparison to previously examined claims:
New claims 108-119 recite steps, techniques and/or formalisms which are beyond the steps and techniques not readily apparent in examined claims 66-76 and 105-107, or the other new claims;
New claims 120-130 recite steps, techniques and/or formalisms which are beyond the steps and techniques not readily apparent in examined claims 66-76 and 105-107, or the other new claims;
New claim 131 recites steps, techniques and/or formalisms which are beyond the steps and techniques not readily apparent in examined claims 66-76 and 105-107, or the other new claims;
New claim 132 recites steps, techniques and/or formalisms which are beyond the steps and techniques not readily apparent in examined claims 66-76 and 105-107, or the other new claims.
There would be serious search and examination burdens on the examiner if the restriction is not required. For example, a quick survey of the new claims’ preambles and limitations indicate that, in addition to expanded and comprehensive patent data base searches, non-patent data base searches would need to iteratively address industrial publications and academic publications (ranging from theses and dissertations to course material, for example, as disclosed in Deisenroth et al. (Mathematics for Inference and Machine Learning, Lecture Notes, Imperial College London, Department of Computing, Version 13 January 2017) and Wang, Sherri (CME 250: Introduction to Machine Learning, Lecture 5: Support Vector Machines, Leland Stanford Junior University, Winter 2019) ).
Since applicant has received an action on the merits for the originally presented invention, this invention has been constructively elected by original presentation for prosecution on the merits. Accordingly, claims 108-132 are withdrawn from consideration as being directed to a non-elected invention. See 37 CFR 1.142(b) and MPEP § 821.03.
To preserve a right to petition, the reply to this action must distinctly and specifically point out supposed errors in the restriction requirement. Otherwise, the election shall be treated as a final election without traverse. Traversal must be timely. Failure to timely traverse the requirement will result in the loss of right to petition under 37 CFR 1.144. If claims are subsequently added, applicant must indicate which of the subsequently added claims are readable upon the elected invention.
Should applicant traverse on the ground that the inventions are not patentably distinct, applicant should submit evidence or identify such evidence now of record showing the inventions to be obvious variants or clearly admit on the record that this is the case. In either instance, if the examiner finds one of the inventions unpatentable over the prior art, the evidence or admission may be used in a rejection under 35 U.S.C. 103 or pre-AIA 35 U.S.C. 103(a) of the other invention.
Response to Arguments
Applicant’s arguments with respect to claims 66-76 and 105-107 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
Examiner’s Comments – Claim Language
Independent claim 66 recites, “a predetermined amplitude scaling factor S.”
Claim 67, which depends upon claim 66, recites, “a minimum detected amplitude that is substantially equal to SN where N is the number of intermediate locations.” Emphases added.
Claim 70, which depends upon claim 69 which depends upon claim 66, recites, “the predetermined amplitude scaling factor S is substantially equal to (k - 1)/k, where k is the number of intermediate locations.” Emphases added.
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 of this title, 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.
The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 66-70 and 74
Claims 66-70 and 74 are rejected under 35 U.S.C. 103 as being unpatentable over Lin et al. (2018/0129082; “Lin”) in view of Imai et al. (2020/0059065; “Imai”), further in view of Wang et al. (Constellation Mapping for Physical-Layer Network Coding with M-QAM Modulation, arXiv:1112.0805v2 [cs.IT] 11 May 2013; “Wang-NPL-2013”), and further in view of Sonkin et al. (MZM Optimization of PAM-4 Transmission in Data Center Interconnect. Appl. Sci. 2019, 9, 637; “Sonkin”).
Regarding claim 66, Lin discloses in figures 4 and 8, and related figures and text, for example, Lin Selected Text, embodiments of a device, and related methods, comprising a bus waveguide 105 adjacent to and acted upon by EA segments 112-1, 112-2, and 112-3, which are driven by drive signals 123-1, 123-2, and 123-3, as output from encoder 122.
“A method relates generally to electro-absorption modulation. In such a method, an input optical signal is received by a waveguide. A modulation code is received corresponding to input data by a segmented electro-absorption modulator. The input optical signal passing through the waveguide is modulated segment-by-segment with the segmented electro-absorption modulator to generate an output optical signal.” Lin, paragraph [0005].
“[W]herein the segmented electro-absorption modulator is configured to compensate for nonlinearity by selecting a first number of the first and second electro-absorption modulation segments for modulation.” Lin, claim 1.
[0040] (“[B]y having EAM segments 112-1 through 112-3 vary in length, amplitude levels may become more distinct, namely more closely represent linear steps.” Lin, paragraph [0040].
“SEAM [segmented electro-absorption modulator ] 120 may be readily used in many optical applications, such as optical links for example, where power consumption is important, as SEAM 120 is an energy-efficient device. For example, SEAM 120 may be used in optical backplanes. Moreover, SEAM 120 may be used in high-speed optical devices, such as optical transmitters and optical interconnects for example. Because SEAM 120 may modulate an optical signal (e.g., light) by electrically changing an absorption coefficient of an optically active material, such as a waveguide 106 formed of GeSi or other optically active material, SEAM 120 may compensate for nonlinearity in an electro-optical response, by having different segment lengths for example, which provides compensation for compatibility between optical and electrical PAM links or domains. Like conventional high-speed EAM modulators, SEAM 120 may be used with a non-return-to-zero (“NRZ”) modulation.” Lin, paragraph [0041].
“In this example, length of EAM segment 112-1 is shorter than length of EAM segment 112-2, and length of EAM segment 112-2 is shorter than length of EAM segment 112-3. This progression from an input waveguide end 156 toward an output waveguide end 157 of longer and longer longitudinal lengths of anode and cathode segment pairs may be used to compensate for nonlinearity of each successive electro-optical response. Thus, by having EAM segments 112-1 through 112-3 vary in length, amplitude levels may become more distinct, namely more closely represent linear steps. SEAMs 120 may be formed for parallel optical signal processing on an SOI wafer 101 with each SEAM 120 having same or different nonlinearity compensation depending on application, such as for same or different types of modulation.” Lin, paragraph [0042].
“In PAM4, four distinct pulse amplitude levels or pulse amplitudes, generally amplitude levels 1, 2, 3, and 4, are represented by two bits each, such as for example 00, 01, 11, and 10 for a Gray code implementation. Each pair of PAM4 bits is called a “symbol”, namely two bits per symbol. When one of such four amplitude levels is transmitted in a symbol period, two bits are transmitted in parallel. For a PAM4 data stream with 2-bits per symbol, each two bits of input data 121 may be encoded into a 3-bit thermometer code for this example. Table I below is an example a modulation code that may be used for encoding of input data 121 for this implementation, namely for mapping 2-bit PAM4 symbols of input data 121 into corresponding 3-bit thermometer drive signals represented with states of bits of drive signals 123-1 through 123-3.” Lin, paragraph [0067].
Lin – Figures 4 and 8, and Selected Text
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Abstract. Systems and methods therefor relating generally to electro-absorption modulation are disclosed. In a system thereof, a waveguide is for propagating an optical signal. A segmented electro-absorption modulator (“SEAM”) includes: a segmented anode having at least two anode segments spaced apart from one another alongside a first side of the waveguide; and a segmented cathode having at least two cathode segments spaced apart from one another alongside a second side of the waveguide corresponding to the at least two anode segments.
Claim 1. An electro-absorption modulation system, comprising: a waveguide for propagating an optical signal; a segmented electro-absorption modulator including: a segmented anode having at first and second anode segments spaced apart from one another alongside a first side of the waveguide; and a segmented cathode having first and second cathode segments spaced apart from one another alongside a second side of the waveguide corresponding to the first and second anode segments; wherein a first electro-absorption modulation segment with a first length includes the first anode segment and the first cathode segment, wherein a second electro-absorption modulation segment with a second length includes the second anode segment and the second cathode segment, and wherein the segmented electro-absorption modulator is configured to compensate for nonlinearity by selecting a first number of the first and second electro-absorption modulation segments for modulation.
[0004] A system relates generally to an electro-absorption modulation system. In such a system, a waveguide is for propagating an optical signal. A segmented electro-absorption modulator includes: a segmented anode having at least two anode segments located spaced apart from one another alongside a first side of the waveguide; and a non-segmented cathode located alongside a second side of the waveguide corresponding to the at least two anode segments.
[0005] A method relates generally to electro-absorption modulation. In such a method, an input optical signal is received by a waveguide. A modulation code is received corresponding to input data by a segmented electro-absorption modulator. The input optical signal passing through the waveguide is modulated segment-by-segment with the segmented electro-absorption modulator to generate an output optical signal.
[0025] FIG. 1 is a block diagram illustratively depicting an end-on cross-sectional view of an exemplary segmented electro-absorption system (“SEAS”) 100 having a segmented electro-absorption modulator (“SEAM”) 120. SEAS 100 may include more than one SEAM 120, though only one SEAM 120 is illustratively depicted for purposes of clarity and not limitation.
[0027] A trench 151 may be formed in silicon layer 103 for forming an optical waveguide (“waveguide”) 106 in and over trench 151. Along those lines, a doped silicon waveguide layer may be deposited and etched to form waveguide 106. Germanium or other optically active material may be added to such doped silicon waveguide layer, such as by growing GeSi or SiGe or other material with sufficient optical properties, for forming waveguide 106 in, over and above trench 151. Even though trench 151 has a semi-octagonal shape in end profile, other shapes may be used for trench 151 in other implementations.
[0028] Adjacent to lower sidewall surfaces 152 on both opposing sides (e.g., right and left sides) of waveguide 106 over an upper surface 153 of silicon layer 103 may be formed a conductive layer 108 to provide anode and cathode contacts respectively for signal busses 109-1 and 199-1. By “adjacent to”, it is generally meant next to, in contact with, or sufficiently proximate to a waveguide to allow an electrical field applied to a segment of such a waveguide to affect an absorption coefficient for such segment for electro-absorption, namely by changing an absorption spectrum by applying an electric field. A dielectric layer 102 may be formed over upper surface 153 and patterned for defining locations for conductive layer 108 to provide signal busses 109-1 and 199-1, including contacts therefor. In the above or another implementation, a silicon layer 103 may be implanted, diffused and/or otherwise impregnated with same or different types of dopants for forming signal busses 109-1 and 199-1.
[0038] FIG. 4 is a block diagram of a top-down cross-sectional view illustratively depicting an exemplary SEAS 100. Waveguide 106 may have an ingress end 156 configured for receiving an input optical signal 113 and an egress end 157 configured for outputting an output optical signal 114. SEAM 120 is a segmented SEAM 120 adjacent to waveguide 106. SEAM 120 includes a plurality of EAM segments, which in this example are EAM segments 112-1 through 112-3, adjacent to waveguide 106. Even though three EAM segments 112-1 through 112-3 are illustratively depicted, generally two or more EAM segments 112 may be implemented.
[0039] SEAM 120 may include a segmented anode 111 and a segmented cathode 110 respectively on opposite sidewalls of waveguide 106. Segmented anode 110 may have at least two anode segments located side-by-side lengthwise spaced apart from one another alongside a side 158 of waveguide 106, and segmented cathode 110 may have at least two cathode segments located side-by-side lengthwise spaced apart from one another alongside a side 159 of waveguide 106 opposite side 158. Anode segments 111-1 through 111-3 may be spaced across waveguide 106 from corresponding cathode segments 110-1 through 110-3 to form pairs to provide EAM segments 112-1 through 112-3, respectively. Generally, pairs of at least two anode segments 111 and at least two cathode segments 110 respectively aligned to one another for providing a series of at least two EAM segments 112 longitudinally alongside waveguide 106.
[0040] In this example, three EAM segments 112 are used for a pulse-amplitude modulation (“PAM”) having four levels, namely PAM4 levels 0 to 3. However, in other implementations, other numbers of EAM segments 112 for other types of amplitude modulation may be used.
[0041] SEAM 120 may be readily used in many optical applications, such as optical links for example, where power consumption is important, as SEAM 120 is an energy-efficient device. For example, SEAM 120 may be used in optical backplanes. Moreover, SEAM 120 may be used in high-speed optical devices, such as optical transmitters and optical interconnects for example. Because SEAM 120 may modulate an optical signal (e.g., light) by electrically changing an absorption coefficient of an optically active material, such as a waveguide 106 formed of GeSi or other optically active material, SEAM 120 may compensate for nonlinearity in an electro-optical response, by having different segment lengths for example, which provides compensation for compatibility between optical and electrical PAM links or domains. Like conventional high-speed EAM modulators, SEAM 120 may be used with a non-return-to-zero (“NRZ”) modulation.
[0042] In this example, length of EAM segment 112-1 is shorter than length of EAM segment 112-2, and length of EAM segment 112-2 is shorter than length of EAM segment 112-3. This progression from an input waveguide end 156 toward an output waveguide end 157 of longer and longer longitudinal lengths of anode and cathode segment pairs may be used to compensate for nonlinearity of each successive electro-optical response. Thus, by having EAM segments 112-1 through 112-3 vary in length, amplitude levels may become more distinct, namely more closely represent linear steps. SEAMs 120 may be formed for parallel optical signal processing on an SOI wafer 101 with each SEAM 120 having same or different nonlinearity compensation depending on application, such as for same or different types of modulation.
[0043] Again, it should be understood that SEAM 120 may be used without a high-speed electrical DAC, such as a modulator driver, to compensate for nonlinearity. Thus, for low-power applications, design challenges associated with designing a low-power high-speed DAC with high resolution may be avoided by using a SEAM 120. Moreover, by using a SEAM 120, design challenges of adaptively adjusting DAC codes to maintain a balanced PAM4 eye diagram may be avoided.
[0044] While same or different lengths of EAM segments 112 may be used for coarse nonlinearity compensation, thermal compensation may additionally be used with such same different lengths for fine nonlinearity adjustment. Thus, the amount of light allowed to pass as optical input signal 113 to optical output signal 114, namely the amount of light absorbed by electro-absorption, may be controlled by activating 0, 1, 2, or 3 of EAM segments 112-1 through 112-3. In this example, EAM segments 112-1 through 112-3 have different lengths for thermometer coding, with none, or one or more of EAM segments 112-1 through 112-3 being active at a time. However, in another implementation, a different type of coding, such as binary coding for example, may be used. Moreover, in another implementation, none or only one EAM segment 112 may be active at a time. Accordingly, it should be understood that many configurations may be implemented depending upon modulation and/or coding used.
[0065] FIG. 8 is a schematic diagram illustratively depicting an exemplary SEAS 100 for a transmitter for an electrical domain. FIG. 8 is further described with simultaneous reference to FIGS. 1 through 8.
[0066] Input data 121 is provided to an encoder 122. In this example, encoder 122 is a PAM4 encoder; however, in another implementation another type of modulation, including without limitation another type of PAM, may be used to encode input data 121 with an encoder. In this example for PAM4, a “high” bit (“Bit_H) drive signal 123-1, a “zero” bit (“Bit_Z”) drive signal 123-2, a “low” bit (“Bit_L”) drive signal 123-3, or a combination of these drive signals may be active at a time or none of these drive signals may be active at a time in response to output from encoder 122, which output is responsive to input data 121.
[0067] In PAM4, four distinct pulse amplitude levels or pulse amplitudes, generally amplitude levels 1, 2, 3, and 4, are represented by two bits each, such as for example 00, 01, 11, and 10 for a Gray code implementation. Each pair of PAM4 bits is called a “symbol”, namely two bits per symbol. When one of such four amplitude levels is transmitted in a symbol period, two bits are transmitted in parallel. For a PAM4 data stream with 2-bits per symbol, each two bits of input data 121 may be encoded into a 3-bit thermometer code for this example. Table I below is an example a modulation code that may be used for encoding of input data 121 for this implementation, namely for mapping 2-bit PAM4 symbols of input data 121 into corresponding 3-bit thermometer drive signals represented with states of bits of drive signals 123-1 through 123-3.
[0068] In this example, an encoded input 126 to SEAM 120 as output from encoder 122 has a greatest amount of controlled electro-optical absorption responsive to a PAM4 11 symbol input of input data 121 resulting in all of bits of drive signals 123-1 through 123-3 being asserted, namely in this example all logic 1s. In this example, an encoded input 126 to SEAM 120 as output from encoder 122 has a least amount of absorption responsive to a PAM4 00 symbol input of input data 121 resulting in none of bits of drive signals 123-1 through 123-3 being asserted, namely in this example all logic 0s. In this example, an encoded input 126 to SEAM 120 as output from encoder 122 has a second to least amount of absorption responsive to a PAM4 01 symbol input of input data 121 resulting in none of bits of drive signals 123-1 and 123-2 being asserted, namely in this example both logic 0s, and a bit of drive signal 123-3 being asserted, namely in this example a logic 1. In this example, an encoded input 126 to SEAM 120 as output from encoder 122 has a second most amount of absorption responsive to a PAM4 10 symbol input of input data 121 resulting in both of bits of drive signals 123-2 and 123-3 being asserted, namely in this example both logic 1s, and a bit of drive signal 123-1 not being asserted, namely in this example a logic 0. However, any encoding may be used, including without limitation a complete reversal of the encoding of Table I, a Gray code version of Table I, or another combination. Generally, various steps in light may be controlled by electro-absorption to provide detectable amplitude levels, whether thermometer, binary, or otherwise encoded.
Further regarding claim 66, Imai discloses in figures 3-4 and 6-7, and related figures and text, for example, Imai Selected Text, embodiments of electro-absorption optical modulators, and related methods.
“An electro-absorption optical modulator (2) modulates the laser light. The electro-absorption optical modulator (2) includes a plurality of electro-absorption regions (2a, 2b, 2c) having different extinction characteristics, whereby the extinction ratio curve of the optical device can be controlled to have a shape with multiple steps that is suited to driving conditions.” Imai, abstract.
“FIG. 4 is a diagram showing modulated voltage levels of the four-level pulse-amplitude-modulation (PAM4) scheme. The four-level pulse-amplitude-modulation is a technique whereby a bit sequence represented by “0” and “1” is modulated and transmitted as a pulse signal having four voltage levels represented by two bits “0” and “1” (such as four levels represented by “00”, “01”, “10”, and “11”).” Imai, paragraph [0026].
“FIG. 6 is a graph showing extinction characteristics of the three electro-absorption regions according to Embodiment 1 of the present invention. FIG. 7 is a graph showing the extinction characteristic and light output waveform of the electro-absorption optical modulator according to Embodiment 1 of the present invention. By synthesizing the extinction characteristics of the three electro-absorption regions 2a, 2h, and 2c shown in FIG. 6, an extinction characteristic including a plurality of inflection points, i.e., a plurality of steps, such as the one shown in FIG. 7, which is extremely difficult to realize with a single electro-absorption region configuration, can be achieved.” Imai, paragraph [0029].
“As described above, according to this embodiment, the electro-absorption optical modulator 2 includes a plurality of electro-absorption regions 2a, 2b, and 2c having different extinction characteristics, whereby the extinction ratio curve of the optical device can be controlled to have a shape with multiple steps that is suited to driving conditions.” Imai, paragraph [0031].
“If the number of the plurality of electro-absorption regions is three, the extinction ratio curve can be controlled to have a shape suited to a four-level pulse-amplitude-modulation scheme as shown on the left side of FIG. 7. This way, the communication quality can be improved and stabilized. Consequently, an optical device suitable for communications with an increased capacity by the use of multiple levels of signals can be provided.”). Imai, paragraph [0032].
Imai – Figures 3, 4, 6, and 7, and Selected Text
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Abstract. A semiconductor laser (1) emits laser light. An electro-absorption optical modulator (2) modulates the laser light. The electro-absorption optical modulator (2) includes a plurality of electro-absorption regions (2a, 2b, 2c) having different extinction characteristics, whereby the extinction ratio curve of the optical device can be controlled to have a shape with multiple steps that is suited to driving conditions.
[0025] FIG. 3 is a block diagram illustrating an optical module according to Embodiment 1 of the present invention. The optical module 12 includes the semiconductor laser 1, the electro-absorption optical modulator 2, a lens 13, and a connector 14. An LD power supply 15 supplies power to the semiconductor laser 1. A driver 16 is a PAM4 pulse generator circuit that generates a pulse signal using a four-level pulse-amplitude-modulation scheme for driving the electro-absorption optical modulator 2 based on the four-level pulse-amplitude-modulation scheme. The output light from the electro-absorption optical modulator 2 is collected by the lens 13 and introduced into an optical fiber connected to the connector 14.
[0026] FIG. 4 is a diagram showing modulated voltage levels of the four-level pulse-amplitude-modulation (PAM4) scheme. The four-level pulse-amplitude-modulation is a technique whereby a bit sequence represented by “0” and “1” is modulated and transmitted as a pulse signal having four voltage levels represented by two bits “0” and “1” (such as four levels represented by “00”, “01”, “10”, and “11”).
[0028] Next, the extinction characteristic of the electro-absorption optical modulator according to this embodiment will be described in comparison to that of a common configuration. FIG. 5 is a graph showing an extinction characteristic and a light output waveform of a common electro-absorption optical modulator. Application of a reverse bias to the electro-absorption optical modulator reduces the amount of emitted laser light. The extinction ratio refers to the ratio of laser light intensities when a reverse bias is applied and when the reverse bias is zero.
[0029] FIG. 6 is a graph showing extinction characteristics of the three electro-absorption regions according to Embodiment 1 of the present invention. FIG. 7 is a graph showing the extinction characteristic and light output waveform of the electro-absorption optical modulator according to Embodiment 1 of the present invention. By synthesizing the extinction characteristics of the three electro-absorption regions 2a, 2h, and 2c shown in FIG. 6, an extinction characteristic including a plurality of inflection points, i.e., a plurality of steps, such as the one shown in FIG. 7, which is extremely difficult to realize with a single electro-absorption region configuration, can be achieved.
[0030] Voltage transitions between the high and the low voltage, i.e., the rising and falling edges of the light output waveform output from the electro-absorption optical modulator 2 are largely affected by the slope of the extinction characteristic. An electro-absorption optical modulator having a typical extinction characteristic and driven by a PAM4 scheme would have a light output waveform such as the one shown on the right side of FIG. 5. On the other hand, the electro-absorption optical modulator 2 of this embodiment has an extinction characteristic with drastic changes in the area of use so that its light output waveform appears as shown on the right side of FIG. 7. Thus a certain eye opening (mask margin) can be secured in each of the three layer waveforms.
[0031] As described above, according to this embodiment, the electro-absorption optical modulator 2 includes a plurality of electro-absorption regions 2a, 2b, and 2c having different extinction characteristics, whereby the extinction ratio curve of the optical device can be controlled to have a shape with multiple steps that is suited to driving conditions.
[0032] If the number of the plurality of electro-absorption regions is three, the extinction ratio curve can be controlled to have a shape suited to a four-level pulse-amplitude-modulation scheme as shown on the left side of FIG. 7. This way, the communication quality can be improved and stabilized. Consequently, an optical device suitable for communications with an increased capacity by the use of multiple levels of signals can be provided.
Consequently, in light of Imai’s disclosure of predictably designing and implementing electro-absorption regions, it would have been obvious to one of ordinary skill in the art to modify Lin’s device and related method embodiments to disclose a method suitable for transmitting information from a plurality of nodes to at least one destination, the method comprising: transmitting a signal having a predetermined preliminary amplitude from a source onto a transmission medium; modulating an amplitude of the signal at each of a plurality of intermediate locations between the source and the destination by a selected modulation value from a binary set of two possible modulation values, where for each of the intermediate locations, the binary set consists of: the modulation value 1, and a predetermined amplitude scaling factor S that is greater than 0 and less than 1; Lin, figures 4 and 8, and related figures and text, for example, Lin Selected Text; Imai, figures 3-4 and 6-7, and related figures and text, for example, Imai Selected Text; because the resultant configuration and related method would facilitate designing, implementing, and deploying pulse amplitude configurations characterized by enhance communication capabilities. Imai, paragraph [0032] (“If the number of the plurality of electro-absorption regions is three, the extinction ratio curve can be controlled to have a shape suited to a four-level pulse-amplitude-modulation scheme as shown on the left side of FIG. 7. This way, the communication quality can be improved and stabilized. Consequently, an optical device suitable for communications with an increased capacity by the use of multiple levels of signals can be provided.”).
Here, the examiner emphasizes that the two-state nature of Lin in view of Imai’s pulse amplitude modulation methods clearly correspond to the instant application’s recited “binary set of two possible modulation values.”
State One (Lin in view of Imai) … an EAM segment ‘does nothing’ …and the amplitude of the light that exits the EAM segment equals the amplitude of the light that had entered the EAM Segment.
State Two (Lin in view of Imai) … an EAM segment ‘fractionally reduces’ the pulse’s amplitude …and the amplitude of the light that exits the EAM segment is less than the amplitude of the light that had entered the EAM Segment.
See Lin, paragraph [0044] (“… the amount of light allowed to pass as optical input signal 113 to optical output signal 114, namely the amount of light absorbed by electro-absorption, may be controlled by activating 0, 1, 2, or 3 of EAM segments 112-1 through 112-3.”) and Imai, paragraph [0028] (“ Application of a reverse bias to the electro-absorption optical modulator reduces the amount of emitted laser light. The extinction ratio refers to the ratio of laser light intensities when a reverse bias is applied and when the reverse bias is zero.”).
Further regarding claim 66, Wang-NPL-2013 discloses in figures 1, 3, and 4, and related figures and text, that for pulse amplitude modulation (4-PAM), “there exists ambiguity between the “10” and “00” bits …’” Wang-NPL-2013, I. Introduction.
And Sonkin discloses in figure 2, and related figures and text, that, “One mechanism of improvement [of PAM-4 transmission] is associated with the optimizing of the transmitted power levels by performing ‘optical uneven PAM’ transmission.” Sonkin, I. Introduction and 3. Analog Optimization Method (“It is well known that the input to output transfer function of optical modulators is usually nonlinear. This non-linearity of the optical modulator can be used in a beneficial way to optimize the power spacing discussed above. …as shown in Figure 2a. Using a lower voltage bias point, of 4.1 V as an example, leads to operation within the non-linear regime. The eye diagrams of two different transmission schemes using two different bias points of 5 V and 4.1 V, in this example, are shown in Figure 2b,c, respectively. In Figure 2c, reducing the bias point to 4.1 V increases the spacing between level 3 and level 2 on account of reducing the spacing between level 1 and level 0, and increases the extinction ratio (ER).”).
Consequently, in light of:
(a) Lin’s disclosure of manipulating EAM segment characteristics such that PAM-4 levels ‘more closely represent linear steps,’
(b) Imai’s disclose that coordinating three segments’ extinction characteristics facilitates improving and stabilizing PAM-4 communication capabilities,
(c) Wang-NPL-2013’s disclosure of potential ambiguities in PAM-4 symbol mapping, for example, ‘the XOR mapping method may …not be suitable for higher level modulations. … there exists ambiguity between the “10” and “00” bits when using XOR mapping,’ and
(d) Sonkin’s disclosure of optimizing PAM-4 power spacing, by manipulating non-linear transfer functions to predictably increase and/or decrease the ‘separation’ between PAM-4 levels;
it would have been obvious to one of ordinary skill in the art to modify Lin in view of Imai’s device and method embodiments to disclose:
a method for transmitting information from a plurality of nodes to at least one destination, the method comprising: transmitting a signal having a predetermined preliminary amplitude from a source onto a transmission medium; modulating an amplitude of the signal at each of a plurality of intermediate locations between the source and the destination by a selected modulation value from a binary set of two possible modulation values, where for each of the intermediate locations, the binary set consists of: the modulation value 1, and a predetermined amplitude scaling factor S that is greater than 0 and less than 1; detecting the signal at the destination after transmission past all of the intermediate locations; and mapping a detected amplitude of the detected signal using a predetermined amplitude scale that indicates a number of intermediate locations at which the signal was modulated by the predetermined amplitude scaling factor; Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text;
because the resulting configurations and methods would facilitate designing, fabricating, and deploying ‘high-speed optical devices, such as optical transmitters and optical interconnects;’ Lin, paragraph [0041]; characterized by improved quality and increased capacity; Imai, paragraph [0032]; and reduced susceptibility to symbol ambiguity; Wang-NPL-2013, I. Introduction; as provided by, for example, optimized PAM-4 power level spacing. Sonkin, 3. Analog Optimization Method.
Wang-NPL-2013, Figures 1, 3, and 4
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Regarding claims 67-70 and 74, as dependent upon claim 66, it would have been obvious to one of ordinary skill in the art to modify Lin in view of Imai, further in view of Wang-NPL-2013, and further in view of Sonkin’s device and method embodiments, as applied in the rejection of claim 66, to disclose:
67. The method of claim 66, wherein the predetermined amplitude scale includes a maximum detected amplitude that is substantially equal to the predetermined preliminary amplitude, and a minimum detected amplitude that is substantially equal to SN where N is the number of intermediate locations. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text.
68. The method of claim 66, wherein the predetermined amplitude scaling factor S is different for each intermediate location. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text.
69. The method of claim 66, wherein the predetermined amplitude scaling factor S is equal for each intermediate location. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text.
70. The method of claim 69, wherein the predetermined amplitude scaling factor S is substantially equal to (k - 1)/k, where k is the number of intermediate locations. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text.
74. The method of claim 66, wherein the transmission medium comprises an optical waveguide. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text.
because the resulting configurations and methods would facilitate designing, fabricating, and deploying ‘high-speed optical devices, such as optical transmitters and optical interconnects;’ Lin, paragraph [0041]; characterized by improved quality and increased capacity; Imai, paragraph [0032]; and reduced susceptibility to symbol ambiguity; Wang-NPL-2013, I. Introduction; as provided by, for example, optimized PAM-4 power level spacing. Sonkin, 3. Analog Optimization Method.
Claims 71-73 and 105-107
Claims 71-73 and 105-107 are rejected under 35 U.S.C. 103 as being unpatentable over Lin et al. (2018/0129082; “Lin”) in view of Imai et al. (2020/0059065; “Imai”), further in view of Wang et al. (Constellation Mapping for Physical-Layer Network Coding with M-QAM Modulation, arXiv:1112.0805v2 [cs.IT] 11 May 2013; “Wang-NPL-2013”), and further in view of Sonkin et al. (MZM Optimization of PAM-4 Transmission in Data Center Interconnect. Appl. Sci. 2019, 9, 637; “Sonkin”), as applied in the rejection of claims 66-70 and 74, and further in view of Shahar et al. (2004/0136714; “Shahar”) and further in view of Wang et al. (QAM classification methods by SVM machine learning for improved optical Interconnection, Optics Communications 444 (2019) 1–8; “Wang-NPL-2019”).
Regarding claims 71-73 and 105-107, Shahar discloses in figures 1-3, and related figures and text, for example, Selected Text, “[An] optical system for decoding, switching, demultiplexing, and routing of optical encoded data symbols, including: a plurality of optical paths having first and second terminals; a splitting mechanism for directing the encoded data symbols to each of the first terminals; a plurality of decoding devices for producing decoded signals in response to the encoded data symbols; and each of the optical paths includes, between the first and second terminals, at least one of the decoding devices to produce one of the decoded signals at one of the second terminals in response to one of the encoded data symbols.” Shahar, abstract. Shahar’s embodiments designed to multiplex/demultiplex symbols with predetermined addresses modulated by any combination of time, phase, and polarization modulation, the embodiments comprising symbol configurations, summing gates, and control pulses for increasing the ratio between coincidence pulses and non-coincidence pulses produced by coincidence gates. Shahar, paragraphs [0029]-[0042].
And Wang-NPL-2019 discloses in figures 1, 2, and 9, and related figures and text, for example, Selected Text, applying the machine learning method of support vector machine (SVM) towards ‘optimizing the classification boundary which is particularly suitable for time-varying channels’ … for example, to ‘realize the optimized QAM classification for a specified optical interconnection link.’ Wang-NPL-2019 Selected Text.
Consequently, in light of Shahar’s disclosure of expanding and enhancing optical modulation methods and Wang-NPL-2019’s disclosure of methods for optimizing optical modulation methods, it would have been obvious to one of ordinary skill in the art to modify Lin in view of Imai, further in view of Wang-NPL-2013, and further in view of Sonkin’s device and method embodiments, as applied in the rejection of claims 67-70 and 74, to disclose:
71. The method of claim 66, wherein the signal transmitted from the source has the predetermined preliminary amplitude within each of a plurality of time slots, including a first time slot. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text; Shahar, figures 1-3, and related figures and text, for example, Selected Text; Wang-NPL-2019, figures 1, 2, and 9, and related figures and text, for example, Selected Text.
72. The method of claim 71, wherein the modulation of the amplitude of the signal at each of the plurality of intermediate locations occurs within the first time slot after a propagation delay based on a propagation distance between each intermediate location and the source. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text; Shahar, figures 1-3, and related figures and text, for example, Selected Text; Wang-NPL-2019, figures 1, 2, and 9, and related figures and text, for example, Selected Text.
73. The method of claim 71, further comprising maintaining time synchronization among the plurality of nodes, the source, and the destination. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text; Shahar, figures 1-3, and related figures and text, for example, Selected Text; Wang-NPL-2019, figures 1, 2, and 9, and related figures and text, for example, Selected Text.
105. The method of claim 66 wherein the signal has a predetermined phase; wherein the method comprises: modulating the phase of the signal at each of the plurality of intermediate locations between the source and the destination by a selected modulation value; and mapping the detected amplitude and detected phase of the detected signal using a predetermined scale that indicates the number of intermediate locations at which the signal was modulated. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text; Shahar, figures 1-3, and related figures and text, for example, Selected Text; Wang-NPL-2019, figures 1, 2, and 9, and related figures and text, for example, Selected Text.
106. The method of claim 66 wherein the signal has a predetermined polarization; wherein the method comprises: modulating the polarization of the signal at each of the plurality of intermediate locations between the source and the destination by a selected modulation value; and mapping the detected amplitude and detected polarization of the detected signal using a predetermined scale that indicates the number of intermediate locations at which the signal was modulated. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text; Shahar, figures 1-3, and related figures and text, for example, Selected Text; Wang-NPL-2019, figures 1, 2, and 9, and related figures and text, for example, Selected Text.
107. The method of claim 66 in which the signal has a predetermined phase and a predetermined polarization; wherein the method comprises: modulating the phase and the polarization of the signal at each of the plurality of intermediate locations between the source and the destination by a selected modulation value; and mapping the detected amplitude, detected phase, and detected polarization of the detected signal using a predetermined scale that indicates the number of intermediate locations at which the signal was modulated. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text; Shahar, figures 1-3, and related figures and text, for example, Selected Text; Wang-NPL-2019, figures 1, 2, and 9, and related figures and text, for example, Selected Text.
because the resulting configurations and methods would facilitate designing, fabricating, and deploying ‘high-speed optical devices, such as optical transmitters and optical interconnects;’ Lin, paragraph [0041]; characterized by improved quality and increased capacity; Imai, paragraph [0032]; and reduced susceptibility to symbol ambiguity; Wang-NPL-2013, I. Introduction; as provided by, for example, optimized PAM-4 power level spacing; Sonkin, 3. Analog Optimization Method; applicable to decoding, switching, demultiplexing, and routing of optical encoded data symbols; Shahar, abstract; in dense systems. Wang-NPL-2019, Selected Text.
Shahar – Figures 1-3, and Selected Text
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Abstract. The present invention provides an optical system for decoding, switching, demultiplexing, and routing of optical encoded data symbols, including: a plurality of optical paths having first and second terminals; a splitting mechanism for directing the encoded data symbols to each of the first terminals; a plurality of decoding devices for producing decoded signals in response to the encoded data symbols; and each of the optical paths includes, between the first and second terminals, at least one of the decoding devices to produce one of the decoded signals at one of the second terminals in response to one of the encoded data symbols.
0029] Another object of the present invention is to provide coincidence gates including summing gates that may sum the control and the data signal and have closed loop clock recovery control;
[0034] Another object of the present invention is to provide symbol configurations, summing gates, and control pulses for increasing the ratio between coincidence pulses and non-coincidence pulses produced by coincidence gates;
[0035] Another object of the present invention is to provide coincidence gates including delay lines;
[0036] Another object of the present invention is to provide coincidence gates including variable delay lines;
[0037] Another object of the present invention is to provide coincidence gates including delay lines compactly produced on a chip;
[0042] Still another object of the present invention is to provide embodiments designed to multiplex/demultiplex symbols with predetermined addresses modulated by any combination of time, phase, and polarization modulation.
[0046] In one embodiment, the E-fields of the two input signals are summed providing an output whose power is up to four times the power of either output when one input alone provides a signal (assuming the two inputs have the same power level);
[0047] In another embodiment, the E-fields of the two input signals are summed. The resultant output is added to a signal generated by a separate source whose E-field magnitude is some fraction of that of the output resulting from coincidence of the inputs and out of phase with it such that the magnitude ratio of the signal at the coincidence output in a coincidence state to the signal in a non-coincidence state is increased. For example, if the E-field of the constant source is one half the magnitude of the non-coincidence signal at the coincidence output and out of phase with it, the energy magnitude of the signal in a coincidence state at the coincidence output will be nine times the magnitude of the non-coincidence signal at that output.
[0048] In a further embodiment, the pulses may be formed such that there is a negative E-field added to them, whose amplitude is, for example, a third of the E-field of the pulses and 180 degrees out of phase. Then, when the pulses are added coherently, the coincidence pulse power level is up to nine times (for the -1/3, +1 example) greater than that of the level of the non-coincidence pulses or the "floor" level between the pulses. In an additional embodiment, pulses with E-fields having different polarizations may be summed to generate, by vector addition, a pulse with a different polarization angle matching that of a polarization filter such that the energy of either component is substantially more attenuated than that of the sum. The ratio between the output energies of the signals in a non-coincidence state and a coincidence state, at the coincidence output, is depend on whether polarization filter is used or not in the output(s) of the control device. It also depends on the relative polarization orientation between the inputs beams. When pulses, whose E-fields at respective inputs are in phase, but with a difference in polarization angle of .pi./2, are summed by a polarizing beam splitter, the above ratio at the output is 4:1 when a polarization filter is used at the output and 2:1 when such a filter is not used. This ratio can be increased to 9:1 by adding CW field, with the appropriate magnitude phase and polarization, to each of the inputs or to the summed outputs. It is also possible to select one of two outputs providing the coincidence behavior by changing the phase of one of the inputs relative to the other.
[0050] Phase modulation is produced by the relative phase between the data and control signals. When a control signal and a data signal are coincident with equal phases, at respective inputs of a control unit, most of the data signal energy is directed to one output (the coincidence output for phase matching). Alternatively, when a control signal and a data signal are coincident with opposite phases, at the same respective inputs of a control unit, most of the data signal energy is directed to the other output (the coincidence output for anti-phase). Accordingly, the appearance of a high-energy signal in one of the outputs of the control unit depends on the coincidence and the phase conditions.
[0051] Polarization modulation is produced by the relative polarization between the data and control signals. When a control signal and a data signal are coherent and polarized along the same direction, at respective inputs of a control unit (even if the control unit is polarization-insensitive), most of the data signal energy is directed to one output: the coincidence output corresponding to phase matching. Alternatively, when the control unit is polarization-sensitive and receives, at its respective inputs, control and data signals that are polarized along directions that are normal to each other, most of the data signal energy is directed to one of the outputs of the control unit. The coincidence output can be selected by the relative polarization orientation and phase between the energy at the inputs of the control unit. Accordingly, the appearance of a high-energy signal in one of the outputs of the control unit depends on the coincidence, the phase, and the polarization conditions.
[0159] FIGS. 1A, 1B, 1C and 1D are figurative illustrations of a gate 100 that directs applied energy, for example, optical energy, based on an interaction between two sources, such as a control source and a source representing data. As discussed below, the gate 100 may permit the selective application of higher energy to an output port based on the timing and configuration of inputs by interaction of the inputs and without the requirement for a state change of the gate 100. A discussion of various embodiments that exhibit this behavior follows the discussion of FIGS. 1A, 1B, 1C and 1D.
[0160] Referring to FIG. 1A, a gate 100 has two inputs 5 and 10 and is configured such that when compatible energy signals are received simultaneously at the inputs 5 and 10, responsive outputs, at an output port 15, is obtained. For example, the inputs may be optical energy pulses whose phases are aligned to constructively interfere within the gate 100 or light beams whose polarization angles are in a predetermined relationship relative to each other and to filters within the gate 100. The gate 100 may be further configured such that if the energy received at the inputs has some other relationship (polarization angles, phase, or relative timing, for example) then a different output is obtained. The gate 100 may also, in embodiments, be configured to generate a different output signal at another output, for example output 20 where some of the energy is directed. For example, when a different relationship between the signals received at the inputs 10 and 5 exists, different signals may be output at such an additional output 20. Although only one additional output 20 is shown, more may be provided, depending on the embodiment.
[0161] In FIG. 1A, an input signal 40 includes an input symbol, represented here by a pulse 35 applied to input 5 of the gate 100. A second input 10 receives a different input symbol, represented here by the absence of a coinciding pulse (i.e., no input signal). An output signal 60, and where present other output signals represented by output 63, are responsive to the input signals. Here the output signals are represented by pulses 70 and 80 generated at outputs 15 and 20, respectively. The output signals are detected by sensors 90 and 95. Although gate 100 has two outputs 15 and 20 from which signals 60 and 63 are emitted and detected by sensors 90 and 95, respectively, a greater or lower number of outputs may be provided as will be clear from the discussion of specific embodiments below.
[0162] Referring now to FIG. 1B, the inputs signals change. Here, a different input signal 25 is represented by a pulse 30 applied to the input 10 of the gate 100 and no signal at input 5. A changed output signal 61 is represented by a pulse 71 generated at the output 15. In the illustrated case, the output may be substantially the same whether there is a pulse at input 5 or at input 10, but not coincident. Referring to FIG. 1C, when pulses 30 and 35 are applied to both inputs 10 and 5, respectively, a different output 62 results, which includes a pulse 72, which is different from either pulse 70 or 71.
[0163] By providing an appropriate detector, such as, detector 90, to the gate 100, it can be determined whether a signal was applied to either input 5 or 10 independently or to both in a certain temporal relationship. This may be determined by detecting the presence of a pulse 72 versus either pulse 70 or 71, for example, by comparing an intensity level of the respective pulses. Thus, for example, if a receiver is configured to detect only pulses of the form 72, a signal modulated to carry data and applied at one of the inputs 5 or 10 may be detected as such at the output 15 only when a "control signal" is applied at the other input 10 or 5 simultaneously and respectively. In this case, for example, a data signal at input 5 may be considered to be passed or blocked depending on the coincidence of a signal at input 10. Thus, one of the inputs can be regarded as a control input and the other as a data input. In FIG. 1C, signals 25 and 40 might be coherent and the relative phase between them might be adjusted in a way that output 20 might not emit any radiation. Note that, depending on the nature of the signals applied at ports 5 and 10, which output is used as the output of interest may be changed. For example, the phase relationship between the input signals 25 and 40 may affect which port 15, 20 would be better used as a more effective one for signaling.
[0164] FIG. 1D illustrates a configuration, similar to that of FIG. 1C, except that both outputs, 15 and 20, are used for signaling. The nature of the signals applied at ports 5 and 10 may create useful signals at both outputs 15 and 20 that may be in a form of signals 83 and 84 carried by beams 66 and 67, respectively. For example, the relative phase between beams 25 and 40 may determine at which output port an enhanced output due to constructive interference appears.
[0165] Referring to FIGS. 2A, 2B and 2C, an embodiment of a device that may exhibit behavior such as gate 100 is a dielectric beam splitter 110. In such an embodiment, the inputs are optical energy. One input 115 (the relative strengths of all inputs and outputs are represented by a complex number indicating relative peak amplitude of their electric fields E-field) is a beam incident from one angle, which results in the generation of reflected and transmitted output ports 112 and 113 with output signals 145 and 150. The phase of the reflected output 150 is shown as .pi./2 radians ahead of that of the input 115 to indicate that a relative change of phase occurs depending on the presence and phase of a second input 160. Each output in FIG. 2A has an intensity of about half that of the input beam intensity due to the effect of the beam splitter 110. The intensity is proportional to the square of the E-field. In FIG. 2B, the input 160 includes pulse 155 whose phase is shown arbitrarily as being .pi./2 radians behind of that of the input 115, produces a similar result of two output signals 165 and 170 emanating from output ports 112 and 113, respectively. The intensities of each of these output signals is about half that of the input 160. Each of the inputs may include respective pulses 125, 155 as illustrated.
[0166] It is assumed that the energy incident on the dielectric beam splitter 110 consists, at least substantially, of a single wavelength of light, although, as discussed below, in further embodiments, they consist of non-coherent radiation such as multiple wavelengths, propagation modes, phases or any combination of them. Where the light signals are non-coherent, the power combination effect is correspondingly different with simple power summing, rather than field summing, taking place.
[0167] Referring to FIG. 2C, when inputs 175 and 180 are incident simultaneously on the dielectric beam splitter 110, an output 197 is generated at output port 112 whose field corresponds to the sum of power of the two inputs 180 and 175. The intensity of the pulse 190 of output 197, being proportional to the square of the field amplitude, is thus four times the intensity of either output 145, 150 165, 170 when only one input signal 115, 160 is applied alone. If an incident signal 115 or 160 contains a pulse 125, 155, then the amplitude of an output pulse 135, 140, 136, 141, is half that of the input pulse 125, 155 when the latter is incident alone. If incident input signals 175 or 180 contain pulses 185, 195, then the amplitude of an output pulse 190, is twice that of either input pulse 185, 195 when the pulses 185, 195 are incident simultaneously. If the beam 197 is taken as the output, the behavior of dielectric beam splitter 110 can be seen to fall within the description of the gate 100 (FIGS. 1A-1D).
[0168] Note that the output may be taken as 145, 165 or 150, 170 as well and still fall within the description of the gate 100, depending on the interpretation of the received signal, the relative phase between input beams 115 and 160, and how data is represented. When using coherent energy, such as light, the energy ratio between the energy of the coincidence pulse, at the coincidence output, and the energy of the non-coincidence pulse at that output is up to four. When using non-coherent light this ratio is up to two. The differences between the above ratios is due to the fact that when using coherent light the control device (gate 100) acts as a field combiner while it acts as a power combiner when using non-coherent light. In addition, when using coherent radiation, the coincidence signal is produced at only one output and the non-coincidence signal is null. Thus the energy that is divided between two outputs, in a non-coincidence situation, is emitted from only one output, in a coincidence situation.
[0169] Note that if the phase of either input signal 175 or 180 is changed by 71, the coincidence output pulse will emanate from the port 113 rather than the port 112. This effect may be used to "direct" the coincidence pulse 190 based on a phase encoding of one or both of the input signals. As will be discussed below, this along with the selective gating effect may be used to perform a communications function as performed by a switch or multiplexer/demultiplexer.
[0178] Referring to FIGS. 5A, 5B and 5C, an optical Y-junction 346 may also exhibit the described properties of the gate 100 of FIGS. 1A-1D. A first input signal 340 may be applied to a first leg 343 with no coincident signal applied to the second leg 344. An output signal 345 may have an intensity magnitude of half that of the input signal 340. Similarly, a second input signal 342 may be applied to the second leg 344 with no coincident signal applied to the first leg 343. In that case, again, an output signal 348 may have an intensity magnitude of half that of the input signal 342. Note that half of the energy is lost to the second propagation mode, in the coupling region 346A, and constitutes a loss, from the device at output 347. When both input signals 340 and 342 are incident simultaneously and in phase, the magnitude of an output signal 350, at output 356, may be sum of the magnitudes of the input signals 340 and 342. In the latter case, the energy in inputs 340 and 342 is coupled only to the first propagation mode, in junction 346A, and all propagates through output 347. Accordingly, when using coherent radiation, the energy of the coincidence output pulse 350 is up to four times higher than the non-coincidence pulses 345, 348, depending on the relative phases of inputs 340 and 342. When using non-coherent radiation for pulses 340, 342 the energy of the coincidence pulse 350 is only up to twice the energy of pulses 345, 348. Vector diagrams 341, 339, 352, 354 and 356 are vectorial presentations of signals 340, 342, 345, 348 and 350, respectively. The values accompanied to the vector diagrams indicate the field amplitudes of the vectors corresponding to the signals that they represent.
[0210] Referring now to FIG. 9E, for some configurations, when using the pulse spacing symbology, it may be preferred for the coincidence pulses of a series of symbols to occur at regular intervals. For example this may be useful for synchronization recovery in a system that receives signals from multiple transmitters each coming from different switches with different gate arrays (note the discussion of multiplexers and demultiplexers below). To ensure the coincidence pulses occur at regular intervals irrespective of the spacing, one of the pulses of every pair forming a symbol may always be placed at the last time slot and the pulse in front of it used to control the spacing. For example, pulse 124A pairs with pulse 124B to form a symbol. The allowed time paces (including times slots t.sub.1 to t.sub.6) are shown at 123 (typ.). Pulse 124C and 124D form another pair defining another symbol. Pulses 124E and 124F form yet another pair. In all cases, the trailing symbol 124A, 124D and 124E are in time slot t.sub.1. This means that even though the delay may vary, the coincidence pulses occur at regular intervals (at time slots t.sub.1). The figure assumes the pulses pass through a gate from left to right. It should be clear that any symbol including pair of spaced pulses may cause the coincidence gate to produce only one coincidence signal. Accordingly, each symbol includes one data pulse and one control pulse. Defining the control pulse and the data pulse within the pulse pair is arbitrary and may be arranged in any configuration. For example, the data pulse may be the first pulse and the control pulse may the second delayed pulse or vice versa.
[0211] Referring to FIGS. 9F and 9G, there are various ways of forming the symbols that may allow symbol selection as discussed above. For example, FIG. 9F shows input symbol 473, corresponding to input signal 450 of FIGS. 9A and 9B, blocked data symbol 475, corresponding to coincidence pulse 472 formed at the output of the coincidence gate of FIG. 9B, and passed data symbol 476, corresponding to signal 466 produced at the output of the coincidence gate of FIG. 9A, all produced by the spaced-pulse modulation scheme discussed above. The zero-level is indicated at 479. But the mirror image of this format, as shown in FIG. 9G, would work equally-well. That is, notches 474 in an otherwise elevated signal level (e.g., voltage, current, intensity, etc.) rather than pulses, may be spaced apart by selected a spacing to create a zero-level 477 (or a level below some maximum threshold) signal that is registered by a receiver as representing data directed to it. Non-zero notches would be treated as artifact. Again, the zero-level is indicated at 479.
[0212] FIG. 9H illustrates another scheme for controlling the output from a coincidence gate to provide for coincidence between a single broad pulse 473A and a series of pulses 473B representing multiple data bits. It may be confirmed by inspection that with appropriate time delay, the broad pulse 473A may be made to coincide with all of the series of pulses 473B to form a series of coincidence pulses 473C. Here the allowed time slots would have to be broad enough ensure that when passed through a gate with a time delay different from that for which the symbol (473A and 473B) was formed (not shown), the non-coincidence output indicated at 473D is formed.
Wang-NPL-2019, Figures 1, 2, and 9, and Selected Text
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Abstract. High-order quadrature amplitude modulation (QAM) formats are very effective for increasing the transmission capacity due to the highly increased spectral efficiency. However, the signal-to-noise-ratio (SNR) hungry and dense constellation of QAM make it very sensitive to nonlinear distortion. The nonlinear decision boundary adaptively generated by machine learning method of support vector machine (SVM) can be effectively used for the classification of the symbols. The different classification methods have different performance in terms of classification complexity. We experimentally investigated five SVM multi-classification methods for machine learning assisted adaptive nonlinear mitigation, including the one versus rest (OvR), the symbol encoding (SE), the binary encoding (BE), the constellation rows and columns (RC), and the in-phase and quadrature components (IQC). The comprehensive results with comparisons are demonstrated, indicating significant nonlinear mitigation with BER reductions. The SVM multi-classifier based on the in-phase and quadrature components is relatively optimal, considering the calculation and storage.
1. Introduction. To meet the increasing demands of high capacity data communication, high-order QAM formats with significantly improved signaling efficiency (spectral efficiency) have been widely used for both intensity modulation- direct-detection (IMDD) and coherent detection solutions. High-order QAM signal makes full use of amplitude and phase for carrying the information, which leads to great improvement of the transmission capacity [1]. However, the very dense constellation of high-order QAM leads to higher demand of SNR, which makes it very sensitive to the nonlinear distortion.
Recently, digital signal processing based on machine learning has been studied for equalization and demodulation of optical interconnection systems [8–18]. In general, SVM-based signal processing is powerful with less complexity than deep learning of neural networks, which makes SVM very suitable for cost-sensitive IMDD optical interconnects. However, SVM has different classification methods from different demands. The different classification methods lead to different performance and complexity, which is important consideration when applying it to specific application scenarios, such as meter-scale multimode interconnection and kilometer-scale single-mode interconnection.
Chen et al. demonstrated SVM decision method to mitigate modulation nonlinearity distortion for PAM-4 and PAM-8 VCSEL-MMF optical link [15]. Adaptive detection of PAM-4 signals modulated by silicon micro-ring modulator (Si-MRM) has also been demonstrated by SVM machine learning detection….
2. SVM principle and classification methods. Fig. 1 shows the ideal decision boundary for the original ideal constellation of 16-QAM modulation (as an example) and the actual decision boundary for a transmitted practical constellation using the SVM decision. Compared with the original ideal constellation, the transmitted practical constellation would be affected by both noise and nonlinearity. Thus, the decision boundary can no longer be a simple straight line for QAM. Therefore, SVM multi-classification to obtain adaptive nonlinear decision boundary is a good solution for optimizing the classification boundary which is particularly suitable for time-varying channels.
2.4.2. CBT-SVM based on binary encoding. Since the QAM constellation symbol is based on binary encoding, the label feature based on binary encoding is also very obvious. The multi-classification is based on whether each bit is 0 or 1. Fig. 6(a) shows the training model for 16-QAM, 15 SVMs are needed, and the hyperplane generated by each SVM does not need all the training set data, which can effectively reduce the training time and improve the precision. When testing, you only need to substitute 4 SVM decision functions to get the result. Given the test set, after SVM 1–4, the test point is judged to be the category 1. Fig. 6(b) shows a schematic diagram of the hyperplane generated by node SVM for the training processing of category 1. The red and green colors respectively indicate the two categories to be distinguished, and the gray indicates the training sample set that is not required to be used.
2.4.3. BT-SVM based on in-phase and quadrature components. According to the in-phase and quadrature component (IQC), the QAM signal is regarded as two PAM signals, which means splitting a binary tree training model into two binary trees to reduce the SVM numbers. Fig. 7 shows the 16-QAM training model which used 15 SVMs spitted to the two simple tree with 3 SVMs, respectively.
4. Conclusion. In this paper, we experimentally investigated and compared five SVM multi-classification methods for machine learning assisted adaptive nonlinear mitigation, including OvR, SE, BE, RC, and IQC. The SVM detection was implemented in a QAM-DMT optical transmission link based on the M-ZM and 10-km SSMF. The results indicate significant nonlinear mitigation with BER reductions and the SVM multi-classifier based on the IQC is relatively optimal, considering the SVM number for training and the support vector number. Our objective of this study is to comprehensively investigate the classification methods of SVM machine learning detection with comparisons, so that we can realize the optimized QAM classification for a specified optical interconnection link.
Claim 75 and 76
Claims 75 and 76, as dependent upon claim 74, are rejected under 35 U.S.C. 103 as being unpatentable over Lin et al. (2018/0129082; “Lin”) in view of Imai et al. (2020/0059065; “Imai”), further in view of Wang et al. (Constellation Mapping for Physical-Layer Network Coding with M-QAM Modulation, arXiv:1112.0805v2 [cs.IT] 11 May 2013; “Wang-NPL-2013”), and further in view of Sonkin et al. (MZM Optimization of PAM-4 Transmission in Data Center Interconnect. Appl. Sci. 2019, 9, 637; “Sonkin”), as applied in the rejection of claims 66-70 and 74, further in view of Anderson et al. (2012/0261813; “Anderson”), and further in view of Bauwelinck et al., Optical Interconnects Set to Achieve Bandwidth Benchmark, Photonics Spectra, Jul 2018 , “Bauwelinck”).
Regarding claims 75 and 76, Anderson discloses in figures 3 and 4, and related figures and text, for example, Selected Text, embodiments of devices and related methods comprising: “A flip-chip assembly (i.e., a flip-chip package) is an integrated circuit device (e.g., a semiconductor chip, a die, etc.) mounted on an organic laminate substrate (i.e., a chip carrier) by controlled collapsed chip connection (i.e., C4) attachment.” Anderson, paragraph [0031].
And Bauwelinck discloses: “Silicon photonics provides a highly integrated platform for incorporating silicon waveguides with active and passive components. Electronic circuits can be fabricated on a separate die and assembled with the silicon photonics circuits using flip-chip assembly methods. … The optical module also needs to interconnect to an application-specific integrated circuit (ASIC) or field-programmable gate array (FPGA) elsewhere in the package through high-density and high-speed electrical interconnects. Therefore, optical and electrical interfaces need to be integrated with the high-speed optical components discussed above, essentially realizing a silicon photonics interposer.” Bauwelinck – Selected Text.
Consequently, in light of Anderson’s disclosure of mounting chips and dies on substrates by controlled collapsed chip connection attachment and Bauwelinck’s disclosure of integrated silicon photonics interposer packages, it would have been obvious to one of ordinary skill in the art to modify Lin in view of Imai, further in view of Wang-NPL-2013, and further in view of Sonkin’s device and method embodiments, as applied in the rejection of claims 67-70 and 74, to disclose:
75. The method of claim 74, wherein the optical waveguide is formed in an integrated circuit interposer that includes metal contacts arranged for electrically coupling to at least one semiconductor die in a controlled collapsed chip connection. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text; Anderson, Figures 3 and 4, and related figures and text, for example, Selected Text; Bauwelinck, Selected Text.
76. The method of claim 75, wherein the selected modulation value at one or more of the intermediate locations is provided based on an electrical signal from the semiconductor die. Lin, figures 4 and 8, and related figures and text; Imai, figures 3, 4, 6, and 7, and related figures and text; Wang-NPL-2013, figures 1, 3, and 4, and related figures and text; Sonkin, figure 2, and related figures and text; Anderson, Figures 3 and 4, and related figures and text, for example, Selected Text; Bauwelinck, Selected Text.
because the resulting configurations and methods would facilitate designing, fabricating, and deploying ‘high-speed optical devices, such as optical transmitters and optical interconnects;’ Lin, paragraph [0041]; for example, as ‘highly integrated platforms for incorporating silicon waveguides with active and passive components;’ Bauwelinck – Selected Text; characterized by improved quality and increased capacity; Imai, paragraph [0032]; and reduced susceptibility to symbol ambiguity; Wang-NPL-2013, I. Introduction; as provided by, for example, optimized PAM-4 power level spacing. Sonkin, 3. Analog Optimization Method; and reduced susceptibility to delamination. Anderson, paragraph [0031].
Anderson, Figures 3 and 4, and Selected Text
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[0031] A flip-chip assembly (i.e., a flip-chip package) is an integrated circuit device (e.g., a semiconductor chip, a die, etc.) mounted on an organic laminate substrate (i.e., a chip carrier) by controlled collapsed chip connection (i.e., C4) attachment. Typically, such assemblies are formed by forming solder bumps on an array of conductive pads on the active surface of the integrated circuit device. The device is then "flipped" and positioned such that the device solder bumps are located adjacent to corresponding solder pads within solder resist openings on an organic laminate substrate. Solder paste within the solder resist openings on the substrate temporarily secures the solder bumps in place. Then, a reflow process is performed to create solder joints that both electrically and mechanically connect the integrated circuit device to the substrate. Conventionally, eutectic leaded solder (Pb-63% Sn) has been used to form the solder joints in flip-chip assemblies. Such leaded solder has the advantage of mitigating coefficient of thermal expansion (CTE) mismatch between the chip and the substrate (i.e., organic laminate) and, thereby preventing wiring layers within the chip from delaminating or other damage from occurring to the chip or the substrate.
[0046] Also disclosed herein are embodiments of a method of forming a reinforced BEOL via farm interconnect structure 250, as described above and illustrated in FIGS. 3-8, on an integrated circuit chip. Specifically, this method can comprise performing front and middle of the line processing of a substrate for formation of an integrated circuit chip according to a design. Following front and middle of the line processing, performing back end of the line (BEOL) wiring level processing, including forming device to device interconnect structures as well as interconnect structures to solder bumps for controlled collapsed chip connection (i.e., C4) to an organic laminate substrate (i.e., a chip carrier). The interconnect structures formed during this BEOL processing can include via farm interconnect structures and at least one of these via farm interconnect structures can comprise a reinforced via farm interconnect structure. Such a reinforced BEOL via farm interconnect structure can be formed according to the method as set forth in the flow diagram of FIG. 9.
Bauwelinck – Selected Text
Researchers from imec and imec/Ghent University in Belgium have investigated several implementations for optical links at ≥400 Gb/s using a silicon (Si) photonics platform. This platform integrates compact, high-speed modulators and photodetectors with electro-optical bandwidths beyond 50 GHz, and can be operated comfortably at 56-Gb/s NRZ (nonreturn-to-zero) single-lane data rates. By adopting higher-order modulation formats, single-channel data rates beyond 100 Gb/s can be realized. Two such complex modulation formats have been explored: the electrical duobinary (EDB) modulation format and the pulse-amplitude modulation format (PAM-4). Finally, the researchers address the electrical and optical packaging challenges in realizing fully integrated 50-GHz silicon photonics interposers, enabling tight integration of future multi-Tb/s optical modules with high-bandwidth logic and memory chips.
Among the main building blocks of optical transceivers are optical modulators, which imprint data signals onto the optical carrier wavelength. Modulators can come in several forms, such as silicon ring modulators, silicon Mach-Zehnder modulators, and GeSi-based electroabsorption modulators — each having their own distinct properties and (dis)advantages. New variations of each of these modulators enable them to operate at 56-Gb/s NRZ, which is a simple two-level, one-bit modulation format, turning the light on or off depending on the bit state (1 or 0).
Finally, a GeSi-based electroabsorption modulator was developed operating in the C-band. Such modulators in general offer a wider optical bandwidth than ring modulators, for instance. Additionally, when designed in a lateral PIN GeSi diode configuration, the same device can be optimized to work as a photodiode. This way, a single-chip silicon photonics transceiver — with both electroabsorption modulators and photodiodes — is achieved, operating with a bandwidth well beyond 50 GHz. A driver with a 2-Vpp swing driver realizes an extinction ratio of ~4 dB with similar optical insertion loss.
The IDLab and the Photonics Research Group team realized a unique solution to enable low-power 112-Gb/s PAM-4 transmission. First, instead of going from bits to an analog signal in the electrical domain, they went from bits in the electrical domain to an analog signal in the optical domain. By using these digital-to-optical converters, the digital-to-analog conversion is postponed to the optical domain. And this significantly reduces the complexity and power consumption at the transmitter side.
Silicon photonics provides a highly integrated platform for incorporating silicon waveguides with active and passive components. Electronic circuits can be fabricated on a separate die and assembled with the silicon photonics circuits using flip-chip assembly methods. However, the optical module should connect to single-mode fibers, with low optical loss and acceptable packaging cost. The optical module also needs to interconnect to an application-specific integrated circuit (ASIC) or field-programmable gate array (FPGA) elsewhere in the package through high-density and high-speed electrical interconnects. Therefore, optical and electrical interfaces need to be integrated with the high-speed optical components discussed above, essentially realizing a silicon photonics interposer.
Key metrics for the optical interface are the optical coupling efficiency, spectral bandwidth, and sensitivity to polarization. For coupling to the single-mode fiber, imec has designed, fabricated, and tested optically broadband edge couplers, leveraging a hybrid platform consisting of a silicon photonic layer combined with a silicon nitride photonic layer. Innovations to the layer stack have enabled an optimized coupling efficiency of better than −2.5 dB for O-band operation, and better than −2 dB for operation in the C- and L-bands with less than 0.5-dB polarization sensitivity.
To enable dense high-speed electrical interconnections over short distances, 10-µm × 100-µm through-silicon vias (TSVs) have been integrated in the imec-developed silicon photonics platform on 300-mm SOI wafers. They connect the ASIC or FPGA to the CMOS driver and TIA circuits through the silicon photonics interposer. Performance measurements reveal high-speed TSVs, with electrical 3-dB bandwidth exceeding 50 GHz.
The silicon photonics interposer technology is suited for compact, low-power, and low-cost transceivers for ≥400-Gb/s optical interconnects. Using the silicon photonics prototyping platform, high-speed modulators and photodetectors have been developed, capable of operating at 56-Gb/s NRZ.
With these devices as key building blocks, single-channel data rates up to 112 Gb/s were demonstrated by using PAM-4, an advanced modulation format proposed by industry for 400-Gb/s optical links. Both NRZ and EDB provide an elegant and realistic alternative for 100-Gb/s single-lane optical channels. And, to enable a true 50-GHz silicon photonics interposer platform, broadband optical and electrical interfaces are proposed to enable efficient coupling with single-mode fiber and electrical chips, respectively.
Conclusion
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/PETER RADKOWSKI/Primary Examiner, Art Unit 2874
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