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 .
DETAILED OFFICE ACTION
Claim Status
Claims 1-20 are pending in this application and are under examination in this Office Action. No claims have been allowed.
Claim Rejections - 35 USC § 112(b)
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION. —The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
Claims 5, 8, 12, 13, 17 and 19 are rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention.
Regarding claim 5,
Claim 5 depends from claim 4 and recites that "the launch power is reduced to a power that balances a mitigation of the self-phase modulation with a minimization of amplified spontaneous emissions." The phrase "balances a mitigation of the self-phase modulation with a minimization of amplified spontaneous emissions" renders the claim indefinite because the claim uses a result-oriented term of degree without providing an objective standard for determining when the launch power satisfies the claimed balance. As written, it is unclear whether "balances" requires an equal tradeoff between two quantities, a mathematical optimum, a local optimum, a global optimum, a selected
operating point, a minimized weighted sum, an acceptable bit-error-rate, an acceptable optical signal-to-noise ratio, a particular nonlinear phase-error value, a particular amplified-spontaneous-emission value, or some other criterion.
The claim does not specify any measurable threshold, ratio, acceptable range, optimization function, launch-power range, signal-to-noise ratio, bit-error-rate value, quality factor, optical signal-to-noise ratio, nonlinear phase error, self-phase-modulation phase shift, amplified-spontaneous-emission level, or other objective boundary by which one of ordinary skill in the art could determine whether the claimed launch power satisfies the recited balancing requirement.
The specification does not cure the ambiguity. The specification states generally that lower launch power may lead to higher amplified spontaneous emissions, that higher launch powers may be limited by nonlinear distortions, and that examples may extrapolate between relatively lower and relatively higher launch powers to identify a launch power for which both amplified spontaneous emissions and distortions due to nonlinearity are minimized or at least brought within acceptable ranges. However, the specification does not define what degree of self-phase-modulation mitigation is required, what degree of amplified-spontaneous-emission minimization is required, what constitutes an acceptable range, or how the tradeoff is measured. Thus, the intrinsic record provides only a desired result rather than an objective boundary for the claimed "balances" limitation. Accordingly, the metes and bounds of claim 5 are not reasonably certain, and claim 5 is indefinite.
Regarding claim 8,
Claim 8 depends from claim 7 and recites that "the launch power is reduced to a power that balances a mitigation of the cross-phase modulation with a minimization of amplified spontaneous emissions." The phrase "balances a mitigation of the cross-phase modulation with a minimization of amplified spontaneous emissions" renders the claim indefinite because the claim uses a result-oriented term of degree without providing an
objective standard for determining when the launch power satisfies the claimed balance. As written, it is unclear whether "balances" requires an equal tradeoff between cross-phase-
modulation mitigation and amplified-spontaneous-emission minimization, a mathematical optimum, a local optimum, a global optimum, a selected operating point, a minimized weighted sum, an acceptable signal-quality value, or some other criterion.
The claim does not specify any measurable threshold, ratio, acceptable range, optimization function, launch-power range, signal-to-noise ratio, bit-error-rate value, quality factor, optical signal-to-noise ratio, nonlinear phase error, cross-phase-modulation phase shift, amplified-spontaneous-emission level, or other objective boundary by which one of ordinary skill in the art could determine whether the claimed launch power satisfies the recited balancing requirement.
The specification does not cure the ambiguity. The specification generally states that lower launch power may lead to higher amplified spontaneous emissions and higher launch powers may be limited by nonlinear distortions, and further states that examples may extrapolate between relatively lower and relatively higher launch powers to identify a launch power for which both amplified spontaneous emissions and distortions due to nonlinearity are minimized or at least brought within acceptable ranges. However, the specification does not identify any objective limit, test, range, formula, or threshold for determining when the mitigation of cross-phase modulation and the minimization of amplified spontaneous emissions are sufficiently balanced. Accordingly, the metes and bounds of claim 8 are not reasonably certain, and claim 8 is indefinite.
Regarding claim 12,
Claim 12 depends from claim 1 and recites that "the cause is the self-phase modulation and a dispersion that cooperate to form a soliton, and the at least one action comprises generating a solitonic pulse that balances the soliton." The phrase "balances the soliton" renders the claim indefinite because the claim does not set forth an objective standard
for determining when a generated solitonic pulse balances the soliton. The claim does not specify whether the generated solitonic pulse must balance nonlinearity, balance dispersion, cancel phase change, stabilize pulse shape, restore a prior waveform, preserve pulse width during propagation, reduce a particular error value, or satisfy another measurable soliton condition.
The claim also does not specify any measurable pulse parameter, such as pulse shape, pulse width, amplitude, phase, chirp, dispersion value, nonlinear length, dispersion length, soliton order, propagation distance, stability criterion, error threshold, or other objective boundary for determining whether the generated solitonic pulse has balanced the soliton.
The specification does not cure the ambiguity. The specification states that, in some cases, both dispersion and self-phase modulation may be present, which creates a soliton, and that a Raman amplifier may be used to generate a solitonic pulse that balances this nonlinearity or balances the soliton. However, the specification does not define what it means to balance a soliton, does not disclose a measurable balance condition, and does not provide a test or threshold for distinguishing a solitonic pulse that balances the soliton from one that does not. The phrase is therefore a desired result rather than a reasonably certain claim boundary. Accordingly, the metes and bounds of claim 12 are not reasonably certain, and claim 12 is indefinite.
Regarding claim 13,
Claim 13 depends from claim 12 and recites that "the solitonic pulse is generated using a Raman amplifier." Claim 13 is indefinite because it depends from claim 12 and therefore incorporates the indefinite limitation "generating a solitonic pulse that balances the soliton." Although claim 13 further specifies that the solitonic pulse is generated using a Raman amplifier, the added recitation identifies only a device or technique for generating the solitonic pulse. It does not define what balance is required, does not identify any measurable soliton condition, and does not cure the lack of
reasonable certainty created by the phrase "balances the soliton." Accordingly, the metes and bounds of claim 13 are not reasonably certain, and claim 13 is indefinite.
Regarding claim 17,
Claim 17 depends from claim 16 and recites that "the launch power is reduced to a power that balances a mitigation of the self-phase modulation with a minimization of amplified
spontaneous emissions." The phrase "balances a mitigation of the self-phase modulation with a minimization of amplified spontaneous emissions" renders the claim indefinite for the same reasons discussed above with respect to claim 5. The claim does not provide an objective standard, measurable threshold, ratio, acceptable range, optimization function, launch-power range, signal-to-noise ratio, bit-error-rate value, quality factor, optical signal-to-noise ratio, nonlinear phase error, self-phase-modulation phase shift, amplified-spontaneous-emission level, or other objective boundary by which one of ordinary skill in the art could determine whether the claimed launch power satisfies the recited balancing requirement.
The specification likewise does not cure the ambiguity because it describes only a general goal of selecting a launch power for which amplified spontaneous emissions and nonlinear distortions are minimized or at least brought within acceptable ranges, without defining the required balance or the acceptable range. Accordingly, the metes and bounds of claim 17 are not reasonably certain, and claim 17 is indefinite.
Regarding claim 19,
Claim 19 depends from claim 14 and recites that "the cause is the self-phase modulation and a dispersion that cooperate to form a soliton, and the at least one action comprises using a Raman amplifier to generate a solitonic pulse that balances the soliton." The phrase "balances the soliton" renders the claim indefinite for the same reasons
discussed above with respect to claim 12. The claim does not set forth an objective standard for determining when a generated solitonic pulse balances the soliton. The
claim does not specify whether the generated solitonic pulse must balance nonlinearity, balance dispersion, cancel phase change, stabilize pulse shape, restore a prior waveform, preserve pulse width during propagation, reduce a particular error value, or satisfy another measurable soliton condition. The claim also does not specify any measurable pulse parameter, such as pulse shape, pulse width, amplitude, phase, chirp, dispersion value, nonlinear length, dispersion length, soliton order, propagation distance, stability criterion, error threshold, or other objective boundary for determining whether the generated solitonic pulse has balanced the soliton. Although claim 19 recites that a Raman amplifier is used to generate the solitonic pulse, the use of a Raman amplifier does not define the required balance condition and does not identify any objective boundary for determining whether the generated pulse satisfies the claimed result. Accordingly, the metes and bounds of claim 19 are not reasonably certain, and claim 19 is indefinite.
Accordingly, claims 5, 8, 12, 13, 17 and 19 are indefinite under 35 U.S.C. 112(b).
Claim Rejections – 35 U.S.C. § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for the 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.
As reiterated by the Supreme Court in KSR, and as set forth in MPEP 2141 (R-01.2024), II, the factual inquiries of Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), applied for establishing a background for determining obviousness under 35 U.S.C. §103, are summarized as follows:
Determining the scope and content of the prior art;
Ascertaining the differences between the prior art and the claims at issue;
Resolving the level of ordinary skill in the pertinent art; and
Considering objective evidence indicative of obviousness or non-obviousness, if present.
This application currently names an inventor. In considering patentability of the claims, the examiner presumes that the subject matter disclosed in the prior art was created by another (i.e., not by the inventive entity) unless proven otherwise. Applicant is advised of the obligation under 37 C.F.R. § 1.56 to point out the inventor and effective filing dates of each claim, and any
evidence of common ownership/assignment as of the effective filing date, so that the examiner may properly 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 claimed invention(s).
Claims 1-3,11, 14-15 and 20 are rejected under 35 U.S.C. § 103 as being unpatentable over Gaudette et al. (US20130236169A1) in view of Honda et al. (US20150288458A1) and Lowery et al. (US8112001B2), further in view of Brener et al. (US6704519B1).
Claim 1
As per claim 1, Gaudette teaches a method in an optical network using coherent optical probes, coherent optical transmitters/receivers, an optical service channel, an optical control plane, and a digital processing block to determine optical channel performance characteristics of optical wavelengths propagating in optical fiber links.
Gaudette states: “The present disclosure provides dynamic performance monitoring systems and methods for optical networks to ascertain optical network health in a flexible and accurate manner. The present invention introduces accurate estimations for optical channel performance characteristics based either on existing channels or with a dynamic optical probe configured to measure characteristics on unequipped wavelengths. Advantageously, the dynamic performance monitoring systems and methods introduce the ability to determine physical layer viability in addition to logical layer viability.” [Gaudette, Abstract; p. 1].
Gaudette states: “In various exemplary embodiments, the present invention provides dynamic performance monitoring systems and methods for optical networks that allow optical network health to be ascertained in a flexible and accurate manner. The present invention introduces accurate estimations for optical channel performance characteristics based either on existing channels or with a dynamic optical probe configured to measure characteristics on unequipped wavelengths.” [Gaudette, ¶ [0035], p. 3].
Gaudette states: “The optical network 100 can further include a control plane 106... The control plane 106 introduces intelligence in an optical transport system. It can perform many functions such as automatic resource discovery, distributing network resource information, establishing and restoring connections dynamically across the network, and the like.” [Gaudette, ¶ [0042], p. 4].
Gaudette states: “The present invention enables the control plane 106 to include additional constraints related to the physical transmission properties of the fiber plant, amplifiers, transceivers, and other optical network elements before determining the validity of a lightpath connection through the network 100.” [Gaudette, ¶ [0046], p. 4].
Gaudette states: “The present invention includes an optical probe element positioned at various points throughout the optical network. The optical probe includes a transmitter and receiver portion. The transmitter portion of the probe produces an optical pulse train modulated with PRBS data, and with a tunable wavelength and duty cycle and repetition
rates selectable to represent signals of interest, i.e. 10G, 20G, 40G, 100G, etc. signals.” [Gaudette, ¶ [0036], p. 3].
Gaudette states: “The receiver portion of the probe uses asynchronous sampling to acquire signal diagrams. A Digital Signal Processor (DSP) analyzes acquired signals as a function of optical power, data rate, and tuned sampling timing, and provides a separable measurement of ASE, SPM, Filter narrowing, Chromatic Dispersion, and Polarization Mode dispersion (PMD) distortions. The measurements are cross-correlated to the propagation computations, which account for exact characteristics of data carrying wavelengths.” [Gaudette, ¶ [0036], p. 3; FIG. 8].
Gaudette states: “What is missing is ability to extract the following: More accurate OSNR measurement; Estimation for residual Chromatic Dispersion; Estimation for Polarization Dependent Loss; Estimation for Polarization Mode Dispersion; Estimation for inter-channel nonlinear effects, such as Cross-Phase Modulation (XPM) and Four Wave Mixing (FWM); Estimation for intra-channel nonlinear effects, such as Self-Phase Modulation (SPM), iXPM, iFWM; and Estimation for possible bandwidth narrowing due to in-line optical filtering.” [Gaudette, ¶¶ [0007] - [0014], p. 1].
Gaudette states: “In an exemplary embodiment, an optical system includes a coherent optical transmitter; a coherent optical receiver; and a digital processing block connected to the coherent optical transmitter and the coherent optical receiver, wherein the digital processing block selectively operates the coherent optical transmitter and the coherent optical receiver as one of an optical probe and an optical service channel.” [Gaudette, ¶ [0018], p. 2].
Gaudette states: “The coherent optical receiver can be configured to tune to one of a plurality of wavelengths, and, when operating as the optical probe, the digital processing block determines optical channel performance characteristics of the one of the plurality of wavelengths. The optical channel performance characteristics can include any of OSNR measurement, residual Chromatic Dispersion, Polarization Dependent Loss, Polarization
Mode Dispersion, inter-channel nonlinear effects, intra-channel nonlinear effects, cross-phase modulation, and bandwidth narrowing.” [Gaudette, ¶ [0018], p. 2].
Honda states: “A digital coherent receiver recovers optical intensity information and phase information from received light by coherent detection. The recovered optical intensity information and phase information are digitalized by an A/D converter, and demodulated by a digital signal processing circuit. The digital signal processing circuit is realized by, for example, a DSP (digital signal processor).” [Honda, ¶ [0004], p. 1].
Honda states: “The front-end circuit 21 generates a digital signal indicating an input optical signal by the coherent detection. The digital signal includes the optical intensity information and the phase information about the input optical signal. That is, the digital signal indicates the I component and the Q component of the input optical signal.” [Honda, ¶ [0038], p. 3].
Lowery states: “A time-varying phase modulation is determined (154), which is a first function, and preferably a linear function, of the transmitted optical power corresponding with the information-bearing signal. The information-bearing signal and the time-varying phase modulation are applied (156) to an optical source in order to generate a corresponding transmitted optical signal having substantially the stated transmitted optical power characteristic. The first function of transmitted optical power is selected so as to mitigate the effect of the non-linearity of the optical channel upon the transmitted optical signal.” [Lowery, Abstract; p. 1].
Lowery states: “In alternative arrangements, a time-varying phase modulation, being a second function of optical power, is computed (162) and applied (164) to a signal received following transmission through a non-linear optical channel. The two alternative arrangements provide, respectively, for pre-compensation and post-compensation of non-linear propagation effects that may be carried out entirely within the electrical domain, for example using digital signal processing techniques.” [Lowery, Abstract; p. 1; FIG. 1B].
Lowery states: “The single step simply applies a phase modulation to the optical signal, wherein the instantaneous phase is a relatively simple function of the instantaneous optical
power. In particular, as the “single step” approximation becomes more accurate... the instantaneous phase is simply proportional to the instantaneous optical power.” [Lowery, col. 3, line 46-col. 4, line 2; p. 4].
Lowery states: “According to particularly preferred embodiments of the invention... the first and/or second functions of optical power are linear functions, whereby the time-varying phase modulation consists of a phase shift which is proportional to instantaneous transmitted or received optical power.” [Lowery, col. 5, lines 36-44; p. 6].
Lowery states: “Typically, the non-linear optical channel consists of a plurality of concatenated optical fibre spans having optical amplifiers disposed therebetween in order to boost the optical signal power as compensation for attenuation within each fibre span. In this particular case, the phase shift is preferably computed as a sum over all spans of the instantaneous optical power at the input of each span, multiplied by a constant which is characteristic of the non-linear properties of the optical fibre making up the corresponding span, multiplied again by an effective length of the span.” [Lowery, col. 5, line 53-col. 6, line 3; p. 6].
Brener states: “Besides chromatic dispersion, Kerr-effect non-linearities inherent within the glass fiber can limit its transmission capabilities. In these non-linearities, the index of refraction increases with the intensity of an applied optical signal. Changes in the fiber index of refraction modulate the phase of an optical signal passing through the fiber, and thereby redistribute the signal frequency spectrum.” [Brener, col. 1, lines 49-55; p. 2].
Brener states: “These non-linearities are usually classified as four-wave mixing (FWM), self-phase modulation (SPM) and cross-phase modulation (XPM). For long distance communication over optical fiber, dispersion and nonlinearities must be controlled, compensated, or suppressed.” [Brener, col. 1, lines 58-63; p. 2].
Accordingly, the cited combination teaches claim 1 as follows. Gaudette teaches the optical-network method, coherent optical probe pulse, coherent optical transmitter/receiver, digital processing block, control plane, and determination of optical-channel performance
characteristics for optical wavelengths propagating in optical fiber links. Honda further teaches calculating phase information from received light by coherent detection and DSP processing because Honda expressly recovers optical intensity information and phase information from received light. Thus, Gaudette in view of Honda teaches calculating, by a processing system including at least one processor, a phase of a light pulse that is propagating along an optical fiber of a fiber broadband communications network. Lowery and Brener teach calculating a change in phase due to optical nonlinearity because Lowery calculates a time-varying nonlinear phase modulation/phase shift as a function of optical power and Brener explains that Kerr-effect nonlinearities change the refractive index and modulate the phase of an optical signal. Gaudette and Brener teach determining the cause of the nonlinear phase change as SPM, XPM, or FWM because Gaudette expressly identifies separable estimation of intra-channel nonlinear effects such as SPM and inter-channel nonlinear effects such as XPM and FWM, while Brener confirms those nonlinearities are Kerr-effect phase nonlinearities. Lowery, Honda, Cornwell, Lockheed, Archambault, and Chraplyvy further teach initiating mitigation actions selected based on the determined nonlinear cause, including nonlinear phase modulation/phase rotation, electronic dispersion compensation, launch-power adjustment, adjacent-channel spacing adjustment, and Raman-assisted soliton support.
Therefore, the cited combination teaches calculating the phase, calculating the nonlinear phase change, determining whether the cause includes SPM, XPM, or FWM, and initiating a mitigation action selected based on the determined nonlinear cause.
One of ordinary skill in the art would have been motivated to combine Gaudette with Lowery, Honda, and Brener because Gaudette expressly identifies a need to measure and estimate nonlinear optical-channel impairments, including SPM, XPM, and FWM, to determine physical-layer viability in an optical network; Honda provides the known coherent receiver and DSP architecture that recovers optical phase information from received light; Lowery provides the known phase-domain nonlinear-compensation technique that calculates and applies a phase shift/phase modulation as a function of optical power; and Brener explains the physical Kerr-effect basis for why SPM, XPM, and FWM modulate optical phase and must be controlled or
compensated. The combination would have predictably used known coherent/DSP phase measurement and known nonlinear phase compensation to improve the optical-network health-monitoring and mitigation system of Gaudette. Such a combination is no more than the predictable use of prior-art elements according to their established functions, namely measuring optical phase/nonlinear impairments, identifying the nonlinear impairment type, and applying a known nonlinear phase-mitigation action to improve signal quality and link viability.
Claim 2
With respect to claim 2, all limitations of claim 1 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 2 additionally expressly teaches that calculating the phase of the light pulse is performed using a transponder pulse. However, within analogous art, Gaudette teaches an optical probe/transceiver pulse train generated by the transmitter portion of the optical probe and processed by the receiver/DSP.
Gaudette states: “The transmitter portion of the probe produces an optical pulse train modulated with PRBS data, and with a tunable wavelength and duty cycle and repetition rates selectable to represent signals of interest, i.e. 10G, 20G, 40G, 100G, etc. signals. The receiver portion of the probe uses asynchronous sampling to acquire signal diagrams. A Digital Signal Processor (DSP) analyzes acquired signals as a function of optical power, data rate, and tuned sampling timing...” [Gaudette, ¶ [0036], p. 3].
Gaudette states: “Note that the probes can be used in conjunction with existing optical transceivers. The existing optical transceivers can also provide optical parameters on the various fiber links over which they are provisioned.” [Gaudette, ¶ [0038], p. 3].
One of ordinary skill in the art would have been motivated to use the optical pulse train generated by Gaudette’s coherent optical probe/transceiver as the transponder pulse used for phase calculation because Gaudette expressly teaches that the probe pulse train is tunable,
selectable to represent traffic signals of interest, and analyzed by a DSP as a function of optical power, data rate, and timing. Since Honda teaches that coherent detection recovers phase information, using such a transponder/probe pulse for calculating phase would have predictably allowed the processing system to measure phase and nonlinear phase impairment in the optical fiber before or during channel provisioning.
Claim 3
With respect to claim 3, all limitations of claim 1 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 3 additionally expressly teaches that the cause is self-phase modulation and the at least one action comprises applying a phase rotator to mitigate the self-phase modulation. However, Gaudette identifies SPM as an intra-channel nonlinear effect to be measured, Brener explains that SPM modulates optical phase, and Lowery teaches applying a phase modulation/phase shift to mitigate optical nonlinearity.
For purposes of this rejection, applying a phase rotator is interpreted as applying a phase-rotation or phase-modulation operation to rotate or shift the phase of the optical/electrical signal for nonlinear phase mitigation, consistent with the broad claim language and the specification’s use of phase correction/rotation to mitigate nonlinear phase-delay-induced loss.
Gaudette states: “Estimation for intra-channel nonlinear effects, such as Self-Phase Modulation (SPM), iXPM, iFWM...” [Gaudette, ¶ [0013], p. 1].
Brener states: “Changes in the fiber index of refraction modulate the phase of an optical signal passing through the fiber, and thereby redistribute the signal frequency spectrum... These non-linearities are usually classified as four-wave mixing (FWM), self-phase modulation (SPM) and cross-phase modulation (XPM).” [Brener, col. 1, lines 52-60; p. 2].
Lowery states: “Application of the time-varying phase modulation may be performed either in the electrical domain, or in the optical domain... subsequently applying the time-varying phase modulation to the resulting optical signal, such as by passing the optical signal though
an optical phase modulator to which the time-varying phase modulation drive signal is applied.” [Lowery, col. 4, lines 27-37; p. 5].
Lowery states: “In a particularly preferred, and computationally efficient, embodiment of the invention, the modulation means includes digital modulation means, such as a hardware or software multiplier, which is configured to apply the phase modulation to the time-sequence of signal values generated in the digital domain.” [Lowery, col. 7, lines 15-22; p. 8].
One of ordinary skill in the art would have been motivated to apply Lowery’s phase modulation/phase-rotation compensation when Gaudette identifies SPM because Brener teaches that SPM is a Kerr-effect nonlinearity that modulates the phase of the optical signal, and Lowery teaches a known phase-shift/phase-modulation compensation technique selected to mitigate optical-channel nonlinearity. The predictable result of applying the phase rotator to the SPM component would have been reduction of the nonlinear phase distortion caused by SPM.
Claim 11
With respect to claim 11, all limitations of claim 1 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 11 additionally expressly teaches applying electronic dispersion compensation to mitigate dispersion of the light pulse. However, within analogous art, Honda expressly teaches digital/electronic dispersion compensation in a coherent receiver.
Honda states: “The waveform distortion correction circuit includes a plurality of dispersion compensators and a plurality of nonlinear compensators. The plurality of dispersion compensators and the plurality of nonlinear compensators are alternately connected. That is, the dispersion compensating process and the nonlinear compensating process are alternately performed on a received optical signal.” [Honda, ¶ [0006], p. 1].
Honda states: “The waveform distortion corrector 22a generates a correction result signal that indicates an optical signal whose waveform distortion has been corrected by performing
a digital arithmetic operation on a digital signal output from the front-end circuit 21...” [Honda, ¶ [0040], p. 3].
Honda states: “Adjusting amount of dispersion compensation of each stage so that detected dispersion value may close to zero.” [Honda, FIG. 8, step S3; p. 9].
Honda states: “Adjusting amount of dispersion compensation and amount of nonlinear compensation of each stage so that error may be minimized.” [Honda, FIG. 9, step S5; p. 10].
One of ordinary skill in the art would have been motivated to apply Honda’s electronic/digital dispersion compensation in the Gaudette/Lowery optical-network compensation system because Gaudette measures residual chromatic dispersion and other impairments, Lowery addresses nonlinear propagation effects, and Honda provides a known DSP-based technique for correcting dispersion in a coherent receiver. The combination would predictably mitigate dispersion of the light pulse and improve recovered signal quality.
Claim 14
As per claim 14, Gaudette in view of Lowery and Honda teaches a non-transitory computer-readable medium storing instructions which, when executed by a processing system including at least one processor, cause the processing system to perform the claimed operations. Gaudette expressly discloses a processor, memory, datastore, and path computation software, and also discloses a digital processing block operating a coherent optical transmitter/receiver as an optical probe/OSC.
Gaudette states: “FIG. 9 is a schematic diagram and illustrates a block diagram of a server configured to, responsive to computer-executable code, perform an optical path computation function according to an exemplary embodiment of the present invention.” [Gaudette, ¶ [0032], p. 3; FIG. 9].
Gaudette states: “The digital processing block can provide the optical channel performance characteristics to an optical control plane for inclusion in an optical path computation function associated with the optical control plane.” [Gaudette, ¶ [0018], p. 2].
Gaudette states: “In yet another exemplary embodiment, a method includes operating a coherent optical probe between a first node and a second node; tuning the coherent optical probe to one of a plurality of wavelengths; measuring optical channel performance characteristics of the one of the plurality of wavelengths utilizing a digital processing block at the second node...” [Gaudette, ¶ [0022], p. 2].
Lowery states: “The two alternative arrangements provide, respectively, for pre-compensation and post-compensation of non-linear propagation effects that may be carried out entirely within the electrical domain, for example using digital signal processing techniques.” [Lowery, Abstract; p. 1].
Honda states: “The digital signal processing circuit is realized by, for example, a DSP (digital signal processor).” [Honda, ¶ [0004], p. 1].
The operations recited in claim 14 correspond substantively to the method steps of claim 1. For the reasons discussed above with respect to claim 1, Gaudette in view of Honda teaches calculating phase information of an optical pulse/light signal using coherent detection and DSP processing; Lowery teaches calculating nonlinear phase modulation/phase shift as a function of optical power and applying that phase-domain correction to mitigate optical nonlinearity; and Gaudette teaches determining SPM, XPM, and FWM as optical channel performance characteristics. It would have been obvious to store those operations as processor-executable instructions on a non-transitory computer-readable medium because the cited art expressly implements optical-path computation, probe processing, coherent receiver processing, and nonlinear compensation using DSPs, controllers, servers, memory, and computer-executable code.
One of ordinary skill in the art would have been motivated to implement the method operations in processor-executable instructions stored on a non-transitory computer-readable
medium because the cited references expressly use digital processing blocks, DSPs, controllers, servers, memory, parameter databases, and path-computation software to perform the same type of optical-network measurement and compensation operations. Storing the instructions on a non-transitory computer-readable medium would have been the ordinary and predictable implementation of the software/DSP functionality taught by Gaudette, Lowery, and Honda.
Claim 15
With respect to claim 15, all limitations of claim 14 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 15 additionally expressly teaches that the cause is at least one of SPM or XPM and the at least one action comprises applying a phase rotator to mitigate the SPM or XPM. However, within analogous art, Gaudette identifies SPM and XPM, Brener and Lockheed explain that they are phase nonlinearities, and Lowery teaches phase modulation/phase shift to mitigate optical-channel nonlinearity.
For purposes of this rejection, applying a phase rotator is interpreted as applying a phase-rotation or phase-modulation operation to rotate or shift the phase of the optical/electrical signal for nonlinear phase mitigation, as discussed above for claims 3 and 6.
Gaudette states: “Estimation for inter-channel nonlinear effects, such as Cross-Phase Modulation (XPM) and Four Wave Mixing (FWM); Estimation for intra-channel nonlinear effects, such as Self-Phase Modulation (SPM), iXPM, iFWM...” [Gaudette, ¶¶ [0012] - [0013], p. 1].
Lowery states: “The first function of transmitted optical power is selected so as to mitigate the effect of the non-linearity of the optical channel upon the transmitted optical signal.” [Lowery, col. 3, lines 25-29; p. 4].
Lowery states: “Application of the time-varying phase modulation may be performed either in the electrical domain, or in the optical domain.” [Lowery, col. 4, lines 27-29; p. 5].
One of ordinary skill would have been motivated to apply Lowery’s phase rotator/phase modulation to mitigate SPM or XPM in the claim-14 processor-executable implementation because Gaudette’s processing determines the nonlinear cause, and Lowery supplies the known phase-domain mitigation action for power-dependent nonlinear phase effects. The predictable result would have been reduced nonlinear phase impairment in the optical signal.
Claim 20
As per claim 20, Gaudette in view of Lowery and Honda teaches the claimed apparatus comprising a processor and a non-transitory computer-readable medium storing instructions. Gaudette’s FIG. 9 illustrates a server including processor, I/O interfaces, network interface, datastore, memory, operating system, and path computation software, and Gaudette further teaches that a digital processing block determines optical-channel performance characteristics from coherent optical probe measurements.
Gaudette states: “FIG. 9 is a schematic diagram and illustrates a block diagram of a server configured to, responsive to computer-executable code, perform an optical path computation function according to an exemplary embodiment of the present invention.” [Gaudette, ¶ [0032], p. 3; FIG. 9].
Gaudette states: “The digital processing block determines optical channel performance characteristics of the one of the plurality of wavelengths. The optical channel performance characteristics can include any of OSNR measurement, residual Chromatic Dispersion, Polarization Dependent Loss, Polarization Mode Dispersion, inter-channel nonlinear effects, intra-channel nonlinear effects, cross-phase modulation, and bandwidth narrowing.” [Gaudette, ¶ [0018], p. 2].
Honda states: “The digital signal processor (DSP) 22 includes a waveform distortion corrector 22a, a data recovery unit 22b, an FEC decoder 22c, and a dispersion monitor 22d. The DSP 22 demodulates the digital signal generated by the front-end circuit 21, and recovers the transmission data.” [Honda, ¶ [0039], p. 3].
Lowery states: “In preferred embodiments, the means for determining a time-varying phase modulation includes digital hardware components and/or memory devices containing software instructions for execution by a corresponding processor, for computing the function of a transmitted optical power characteristic corresponding with the information-bearing signal.” [Lowery, col. 7, lines 4-12; p. 8].
The operations recited in claim 20 are the same substantive operations recited in claim 1 and claim 14. As explained for claim 1, Gaudette in view of Honda teaches calculating phase information of a light pulse in an optical fiber network; Lowery teaches calculating the nonlinear phase change/phase modulation as a function of optical power; Gaudette teaches determining SPM, XPM, and FWM; and Lowery teaches initiating a phase-domain mitigation action.
It would have been obvious to implement these operations in an apparatus including a processor and non-transitory computer-readable medium because Gaudette, Honda, and Lowery expressly implement optical-network computation and compensation using processors, DSPs, memory, controllers, and software instructions.
Claims 4, 6, 7, 9-10, 16, 18 are rejected under 35 U.S.C. § 103 as being unpatentable over Gaudette et al., in view of Honda et al., and Lowery et al., further in view of Brener et al., Cornwell et al. (US20020063949A1) and Lockheed Martin Corporation (WO0213432A1).
Claim 4
With respect to claim 4, all limitations of claim 3 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 4 additionally expressly teaches that the action further comprises reducing a launch power of the light pulse simultaneously with applying the phase rotator. However, within analogous art, Lowery teaches that higher launch power increases optical
nonlinearity, and Cornwell teaches reducing nonlinear interaction by decreasing signal channel power.
Lowery states: “The spacing between amplifiers may be increased by launching higher optical power into the fibre spans at the output of the transmitter, and of each amplifier. However, the use of high launch powers increases the effect of optical non-linearities, resulting in higher optical signal distortion, which ultimately limits the received signal quality...” [Lowery, col. 2, lines 3-10; p. 2].
Cornwell states: “The maximum signal launch power is limited to powers below which nonlinear interactions do not cause unacceptable signal degradation. The spacing of the channels as well as other factors, such as the signal channel polarization, affect the maximum signal launch power.” [Cornwell, ¶ [0012], p. 1].
Cornwell states: “Nonlinear interactions in LD fiber can be decreased in the system by increasing the spacing between adjacent channels or decreasing the signal channel power. However, increasing the channel spacing generally reduces the total number of channels in the system. Likewise, decreasing the signal channel power generally requires a corresponding decrease in the amplifier spacing and the transmission distance between electrical regeneration sites.” [Cornwell, ¶ [0018], p. 2].
One of ordinary skill in the art would have been motivated to reduce launch power simultaneously with applying Lowery’s phase rotator because both actions address the same power-dependent nonlinear phase impairment from complementary directions: phase rotation compensates the nonlinear phase distortion already produced, while launch-power reduction decreases the generation of additional nonlinear phase distortion. Combining the two would have predictably improved nonlinear impairment mitigation while avoiding unacceptable signal degradation caused by excessive launch power.
Claim 6
With respect to claim 6, all limitations of claim 1 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 6 additionally expressly teaches that the cause is cross-phase modulation and the at least one action comprises applying a phase rotator to mitigate the cross-phase modulation. However, within analogous art, Gaudette identifies XPM as an inter-channel nonlinear effect to be measured, Lockheed defines XPM as phase distortion caused by a coincident pulse in another WDM channel, and Lowery teaches applying phase modulation/phase shift to mitigate nonlinearity.
For purposes of this rejection, applying a phase rotator is interpreted as applying a phase-rotation or phase-modulation operation to rotate or shift the phase of the optical/electrical signal for nonlinear phase mitigation. This interpretation is used only for the prior-art analysis and is consistent with Lowery’s disclosure of applying a time-varying phase modulation or phase shift to mitigate optical-channel nonlinearity.
Gaudette states: “Estimation for inter-channel nonlinear effects, such as Cross-Phase Modulation (XPM) and Four Wave Mixing (FWM)...” [Gaudette, ¶ [0012], p. 1].
Lockheed states: “Cross-phase modulation is defined as the distortion of the optical phase within a pulse caused by a coincident pulse from another wavelength division multiplexed channel. The more closely spaced the optical channels, the more severe the cross phase modulation.” [Lockheed, p. 2, lines 19-22].
Lowery states: “The first function of transmitted optical power is selected so as to mitigate the effect of the non-linearity of the optical channel upon the transmitted optical signal.” [Lowery, col. 3, lines 25-29; p. 4].
Lowery states: “The time-varying phase modulation consists of a phase shift which is proportional to instantaneous transmitted or received optical power.” [Lowery, col. 5, lines 39-43; p. 6].
One of ordinary skill in the art would have been motivated to apply Lowery’s phase-rotation/phase-modulation compensation when Gaudette identifies XPM because Lockheed
teaches that XPM is phase distortion within a pulse caused by a pulse from another WDM channel. Since Lowery teaches a phase-shift compensation as a function of optical power, and XPM is a power-dependent inter-channel phase effect, applying a phase rotator to mitigate XPM would have been an obvious and predictable use of a known phase-compensation technique for a known phase impairment.
Claim 7
With respect to claim 7, all limitations of claim 6 are taught by Gaudette, Honda, Lowery, Brener, Cornwell and Lockheed except wherein claim 7 additionally expressly teaches that the at least one action further comprises reducing launch power simultaneously with applying the phase rotator. However, within analogous art, Lowery teaches that high launch power increases optical nonlinearity, Cornwell teaches decreasing signal-channel power to decrease nonlinear interactions, and Lockheed teaches that XPM is a phase distortion caused by WDM-channel interaction.
Lockheed states: “Cross-phase modulation is defined as the distortion of the optical phase within a pulse caused by a coincident pulse from another wavelength division multiplexed channel. The more closely spaced the optical channels, the more severe the cross phase modulation.” [Lockheed, p. 2, lines 19-22].
Lowery states: “However, the use of high launch powers increases the effect of optical non-linearities, resulting in higher optical signal distortion, which ultimately limits the received signal quality...” [Lowery, col. 2, lines 6-10; p. 2].
Cornwell states: “Nonlinear interactions in LD fiber can be decreased in the system by increasing the spacing between adjacent channels or decreasing the signal channel power.” [Cornwell, ¶ [0018], p. 2].
One of ordinary skill in the art would have been motivated to reduce launch power while applying phase rotation for XPM mitigation because XPM strength depends on power in adjacent WDM channels, while phase rotation addresses the resulting phase distortion. The
combined use of power reduction and phase rotation would have predictably reduced the creation of XPM and corrected the XPM phase impairment already present.
Claim 9
With respect to claim 9, all limitations of claim 1 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 9 additionally expressly teaches that the cause is four-wave mixing and the action comprises adjusting a spacing between adjacent channels of the optical fiber. However, within analogous art, Gaudette identifies FWM as an inter-channel nonlinear effect, Lockheed expressly teaches that FWM in WDM systems places limits on optical channel spacing, and Cornwell teaches decreasing nonlinear interaction by increasing adjacent-channel spacing.
Gaudette states: “Estimation for inter-channel nonlinear effects, such as Cross-Phase Modulation (XPM) and Four Wave Mixing (FWM)...” [Gaudette, ¶ [0012], p. 1].
Lockheed states: “Four wave mixing is classical mixing of the different optical channels due to the nonlinear fiber medium, and will occur regardless of modulation format, even with unmodulated optical carriers. In an equally spaced wavelength division multiplexed system, the mixing products will fall on top of adjacent channels. This effect places limits on launched optical power and optical channel spacing.” [Lockheed, p. 3, lines 1-6].
Cornwell states: “Nonlinear interactions in LD fiber can be decreased in the system by increasing the spacing between adjacent channels or decreasing the signal channel power.” [Cornwell, ¶ [0018], p. 2].
One of ordinary skill in the art would have been motivated to adjust adjacent-channel spacing when Gaudette identifies FWM because Lockheed expressly teaches that FWM in equally spaced WDM systems produces mixing products that fall on adjacent channels and places limits on optical channel spacing. Cornwell confirms that increasing adjacent-channel spacing is a known way to reduce nonlinear interactions. Thus, using channel-spacing adjustment as the
selected action for an FWM cause would have been a direct and predictable application of known WDM nonlinear mitigation principles.
Claim 10
With respect to claim 10, all limitations of claim 1 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 10 additionally expressly teaches that the cause is cross-phase modulation and the action comprises adjusting spacing between adjacent channels of the optical fiber. However, within analogous art, Lockheed expressly teaches that XPM becomes more severe when optical channels are closely spaced, and Cornwell teaches increasing adjacent-channel spacing to decrease nonlinear interactions.
Lockheed states: “Cross-phase modulation is defined as the distortion of the optical phase within a pulse caused by a coincident pulse from another wavelength division multiplexed channel. The more closely spaced the optical channels, the more severe the cross phase modulation.” [Lockheed, p. 2, lines 19-22].
Cornwell states: “High rates of dispersion tend to decrease nonlinear interactions between closely spaced wavelengths, because the relative velocity of the channels, or “walk-off”, decreases the interaction time between the channels. In LD fiber there is much less walk-off between adjacent closely spaced channels resulting in longer interaction time between channels, which increases the nonlinear interaction and resulting degradation of the signal channels.” [Cornwell, ¶ [0017], p. 2].
Cornwell states: “Nonlinear interactions in LD fiber can be decreased in the system by increasing the spacing between adjacent channels or decreasing the signal channel power.” [Cornwell, ¶ [0018], p. 2].
One of ordinary skill in the art would have been motivated to adjust adjacent-channel spacing when XPM is determined because Lockheed teaches that XPM becomes more severe when optical channels are more closely spaced, and Cornwell teaches increasing adjacent-channel
spacing as a known method to reduce nonlinear interactions. The predictable result would have been reduced inter-channel phase distortion caused by XPM.
Claim 16
With respect to claim 16, all limitations of claim 15 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 16 additionally expressly teaches reducing launch power of the light pulse simultaneously with applying the phase rotator. However, within analogous art, Lowery and Cornwell teach launch-power reduction/power limitation for nonlinear mitigation.
Lowery states: “However, the use of high launch powers increases the effect of optical non-linearities, resulting in higher optical signal distortion, which ultimately limits the received signal quality...” [Lowery, col. 2, lines 6-10; p. 2].
Cornwell states: “The maximum signal launch power is limited to powers below which nonlinear interactions do not cause unacceptable signal degradation.” [Cornwell, ¶ [0012], p. 1].
Cornwell states: “Nonlinear interactions in LD fiber can be decreased in the system by increasing the spacing between adjacent channels or decreasing the signal channel power.” [Cornwell, ¶ [0018], p. 2].
One of ordinary skill would have been motivated to reduce launch power simultaneously with applying a phase rotator in a computer-readable-medium implementation because the processor executing the claim-14 operations would already determine the nonlinear cause and initiate a mitigation action. Combining Lowery’s phase-domain nonlinear compensation with Cornwell’s signal-power reduction would have predictably reduced the nonlinear phase effect at its source while also correcting residual phase distortion.
Claim 18
With respect to claim 18, all limitations of claim 14 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 18 additionally expressly teaches that the cause is at least one of XPM or FWM and the action comprises adjusting spacing between adjacent channels of the optical fiber. However, within analogous art, Lockheed and Cornwell expressly teach the channel-spacing relationship for XPM and FWM.
Lockheed states: “The more closely spaced the optical channels, the more severe the cross phase modulation.” [Lockheed, p. 2, lines 21-22].
Lockheed states: “In an equally spaced wavelength division multiplexed system, the mixing products will fall on top of adjacent channels. This effect places limits on launched optical power and optical channel spacing.” [Lockheed, p. 3, lines 3-6].
Cornwell states: “Nonlinear interactions in LD fiber can be decreased in the system by increasing the spacing between adjacent channels or decreasing the signal channel power.” [Cornwell, ¶ [0018], p. 2].
One of ordinary skill would have been motivated to adjust adjacent-channel spacing when XPM or FWM is determined because the cited art expressly teaches the relationship between channel spacing and both XPM severity and FWM mixing products. The predictable result would be reduced inter-channel nonlinear phase distortion and fewer nonlinear mixing products falling on adjacent channels.
Claims 5, 8 and 17 are rejected under 35 U.S.C. § 103 as being unpatentable over Gaudette et al., in view of Honda et al., and Lowery et al., further in view of Brener et al., Cornwell et al., and Lockheed Martin Corporation, and further in view of Archambault et al. (US10411796B1).
Claim 5
With respect to claim 5, all limitations of claim 4 are taught by Gaudette, Honda, Lowery, Brener, Cornwell and Lockheed, except wherein claim 5 additionally expressly teaches that the launch power is reduced to a power that balances a mitigation of the self-phase modulation with a minimization of amplified spontaneous emissions. However, within analogous art, Lowery teaches the launch-power/nonlinear-distortion tradeoff, Cornwell teaches limiting launch power to avoid nonlinear degradation, and Archambault teaches measurement-based launch-power optimization using nonlinear/SRS and ASE-related measurements.
For purposes of prior-art rejection only, and without withdrawing the above 35 U.S.C. § 112(b) rejection, claim 5 is interpreted as requiring selection of a reduced launch-power operating point that mitigates SPM-related nonlinear phase distortion while also avoiding unacceptable ASE/noise performance.
Lowery states: “Specifically, in order to maintain a high optical signal-to-noise ratio the propagating signal power must be maintained at a sufficiently high level at the input to each optical amplifier in the system... However, the use of high launch powers increases the effect of optical non-linearities, resulting in higher optical signal distortion...” [Lowery, col. 1, line 65-col. 2, line 9; p. 2].
Cornwell states: “The maximum signal launch power is limited to powers below which nonlinear interactions do not cause unacceptable signal degradation... The minimum signal power is determined based on the minimum acceptable signal to noise ratio required to reliably transmit information through the system.” [Cornwell, ¶ [0012], p. 1].
Archambault states: “The fiber SRS measurements relate to fiber nonlinearity... This can result in a large uncertainty in terms of determining the optimal channel launch power in each span based on nonlinear measurements.” [Archambault, col. 1, line 56-col. 2, line 3; p. 15].
Archambault states: “The one or more components can include i) an optical amplifier, and ii) at least one device configured to provide an optical wavelength outside of amplification bandwidth of the optical amplifier, and the performing one or more measurements can include measuring power P1 of the optical wavelength at a downstream node from the optical node with the optical amplifier disabled; measuring power P2 of the optical wavelength at the downstream node with the optical amplifier configured to generate Amplified Stimulated Emission (ASE); and determining Stimulated Raman Scattering (SRS) based on the measured power P1 and power P2.” [Archambault, col. 2, lines 40-51; p. 15].
Archambault states: “The SRS can be scaled based on fiber length and using an attenuation coefficient of the optical fiber and used to determine the launch power into the optical fiber.” [Archambault, col. 3, lines 41-45; p. 16].
Archambault states: “The fiber SRS measurement and the fiber dispersion measurement can be used to automatically optimize launch power of optical signals on a per-span basis.” [Archambault, col. 6, lines 41-48; p. 17].
One of ordinary skill in the art would have been motivated to reduce launch power to a level that balances SPM mitigation and ASE minimization because Lowery teaches that higher launch power worsens nonlinear distortion while sufficient optical power is needed to maintain signal-to-noise ratio; Cornwell teaches maximum launch-power limits and minimum signal-power requirements; and Archambault provides a known measurement-based technique for determining launch power using nonlinear/SRS and ASE-related measurements. Thus, the claimed “balance” would have been a predictable optimization of a result-effective variable, launch power, to reduce nonlinear phase distortion from SPM while avoiding unacceptable ASE/noise performance.
Claim 8
With respect to claim 8, all limitations of claim 7 are taught by Gaudette, Honda, Lowery, Brener, Cornwell and Lockheed, except wherein claim 8 additionally expressly teaches that the launch power is reduced to a power that balances a mitigation of the cross-phase modulation with a minimization of amplified spontaneous emissions. However, within analogous art, Lockheed teaches that XPM is worsened by close WDM-channel interactions, Lowery and Cornwell teach power/nonlinearity tradeoffs, and Archambault teaches measurement-based launch-power optimization accounting for ASE and nonlinear/SRS measurements.
For purposes of prior-art rejection only, and without withdrawing the above 35 U.S.C. § 112(b) rejection, claim 8 is interpreted as requiring selection of a reduced launch-power operating point that mitigates XPM-related nonlinear phase distortion while also avoiding unacceptable ASE/noise performance.
Lockheed states: “Cross-phase modulation is defined as the distortion of the optical phase within a pulse caused by a coincident pulse from another wavelength division multiplexed channel. The more closely spaced the optical channels, the more severe the cross phase modulation.” [Lockheed, p. 2, lines 19-22].
Lowery states: “However, the use of high launch powers increases the effect of optical non-linearities, resulting in higher optical signal distortion, which ultimately limits the received signal quality...” [Lowery, col. 2, lines 6-10; p. 2].
Archambault states: “The one or more measurements can include a measurement of power P1 of the optical wavelength at a downstream node from the optical node with the optical amplifier disabled; a measurement of power P2 of the optical wavelength at a downstream node from the optical node with the optical amplifier configured to generate Amplified Stimulated Emission (ASE); and a determination of Stimulated Raman Scattering (SRS) based on the measured power P1 and power P2.” [Archambault, col. 3, lines 32-42; p. 16].
Archambault states: “The fiber SRS measurement and the fiber dispersion measurement can be used to automatically optimize launch power of optical signals on a per-span basis.” [Archambault, col. 6, lines 41-48; p. 17].
One of ordinary skill would have been motivated to balance XPM mitigation with ASE minimization because XPM is an inter-channel power-dependent nonlinear phase effect and ASE/noise performance depends on sufficient optical signal power. The cited references collectively teach reducing power to reduce nonlinear interaction while selecting launch power based on measured nonlinear/SRS and ASE-related characteristics. Applying those teachings to XPM would have predictably reduced cross-phase modulation while maintaining acceptable amplified spontaneous emission/noise performance.
Claim 17
With respect to claim 17, all limitations of claim 16 are taught by Gaudette, Honda, Lowery, Brener, Cornwell and Lockheed, except wherein claim 17 additionally expressly teaches that the launch power is reduced to a power that balances mitigation of SPM with minimization of ASE. The limitation is taught by Lowery, Cornwell, and Archambault for the same reasons set forth above for claim 5, applied to the computer-readable-medium implementation of claim 14.
For purposes of prior-art rejection only, and without withdrawing the above 35 U.S.C. § 112(b) rejection, claim 17 is interpreted as requiring processor-executable instructions for selecting a reduced launch-power operating point that mitigates SPM-related nonlinear phase distortion while also avoiding unacceptable ASE/noise performance.
Lowery states: “Specifically, in order to maintain a high optical signal-to-noise ratio the propagating signal power must be maintained at a sufficiently high level at the input to each optical amplifier in the system... However, the use of high launch powers increases the effect of optical non-linearities, resulting in higher optical signal distortion...” [Lowery, col. 1, line 65-col. 2, line 9; p. 2].
Cornwell states: “The maximum signal launch power is limited to powers below which nonlinear interactions do not cause unacceptable signal degradation... The minimum signal power is determined based on the minimum acceptable signal to noise ratio required to reliably transmit information through the system.” [Cornwell, ¶ [0012], p. 1].
Archambault states: “The fiber SRS measurement and the fiber dispersion measurement can be used to automatically optimize launch power of optical signals on a per-span basis.” [Archambault, col. 6, lines 41-48; p. 17].
One of ordinary skill would have been motivated to implement this launch-power balance in the computer-readable-medium implementation because the processor-executed operations of claim 16 already include applying a phase rotator and reducing launch power; Archambault provides a known measurement-based way to set the reduced launch power while accounting for nonlinear/SRS and ASE/noise effects; and Lowery/Cornwell establish that launch power is a result-effective variable balancing nonlinear distortion and signal/noise performance. The claimed subject matter would have been obvious as a predictable optimization of launch power in the same optical-fiber nonlinear compensation environment.
Claims 12, 13 and 19 are rejected under 35 U.S.C. § 103 as being unpatentable over Gaudette et al., in view of Honda et al., and Lowery et al., further in view of Brener et al., Cornwell et al., and Lockheed Martin Corporation, and further in view of Chraplyvy et al. (US6191877B1).
Claim 12
With respect to claim 12, all limitations of claim 1 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 12 additionally expressly teaches that the cause is SPM and a dispersion that cooperate to form a soliton, and that the action comprises generating a solitonic pulse that balances the soliton. However, within analogous art, Lowery teaches the combined relevance of nonlinear phase effects and dispersion compensation in optical fiber
transmission, Brener teaches that dispersion and Kerr nonlinearities including SPM must be controlled or compensated, and Chraplyvy expressly teaches soliton systems requiring operation within a critical intensity range to maintain pulse shape and Raman amplification as a solution for maintaining signal intensity.
For purposes of prior-art rejection only, and without withdrawing the above 35 U.S.C. § 112(b) rejection, claim 12 is interpreted as requiring generation or support of a solitonic pulse so that the nonlinear SPM effect and dispersion are maintained in a condition that preserves or stabilizes the solitonic pulse shape during propagation.
Lowery states: “Furthermore, linear dispersion processes, such as chromatic dispersion, may be compensated at any convenient point in a transmission system... using a variety of linear means.” [Lowery, col. 1, lines 21-25; p. 2].
Lowery states: “The single step simply applies a phase modulation to the optical signal, wherein the instantaneous phase is a relatively simple function of the instantaneous optical power.” [Lowery, col. 3, lines 48-52; p. 4].
Brener states: “For long distance communication over optical fiber, dispersion and nonlinearities must be controlled, compensated, or suppressed.” [Brener, col. 1, lines 60-63; p. 2].
Brener states: “One prior art technique for overcoming the presence of these nonlinearities is the use of mid-span optical phase conjugation. Because the phase conjugate of an optical pulse is, in effect, a time reversal of the pulse, an optical phase conjugator placed at the midpoint of an optical fiber span allows the first-order group velocity dispersion of the first half of the span to be compensated by the identical first-order group velocity dispersion produced as the conjugated signal propagates along the second half of the span.” [Brener, col. 2, lines 14-22; p. 2].
Chraplyvy states: “Needs of Soliton Systems, which require operation within a critical intensity range to maintain pulse shape, at any system wavelength (at 1550 nm as well as
1310 nm), are not easily satisfied with the EDFA. It has been recognized for Some time that Raman amplification, in principle, offers a Solution. Postulated Soliton Systems have used the entire fiber as the Raman amplification medium, with pump injection points at 20-60 km Spacing to maintain Signal intensity sufficiently constant.” [Chraplyvy, col. 1, lines 18-30; p. 3].
Chraplyvy states: “A reliable, truly distributed, fiber amplifier would avoid the alternating increasing and decreasing intensities of lumped amplifiers and lessen non-linear effects in conventional Systems as well.” [Chraplyvy, col. 1, lines 31-35; p. 3].
Chraplyvy states: “Raman Amplification--Amplification by which energy is transferred from an electromagnetic pump wave to a lower frequency Signal wave via a molecular vibration. The responsible mechanism is stimulated Raman scattering (SRS).” [Chraplyvy, col. 2, lines 27-31; p. 3].
One of ordinary skill in the art would have been motivated to use Raman-assisted solitonic pulse generation/support when Gaudette/Lowery determine SPM and dispersion-related nonlinear phase impairment because soliton transmission in optical fibers depends on maintaining a balance between nonlinear phase effects and dispersion so that the pulse maintains its shape. Chraplyvy expressly teaches that soliton systems require operation within a critical intensity range to maintain pulse shape and that Raman amplification offers a solution by using the fiber as the Raman amplification medium to maintain signal intensity sufficiently constant. Brener further teaches that Kerr-effect nonlinearities, including SPM, XPM, and FWM, and dispersion must be controlled, compensated, or suppressed in long-distance optical fiber communication. Thus, under the prior-art interpretation stated above, combining the known Raman/soliton teaching of Chraplyvy with Gaudette’s cause determination and Lowery’s nonlinear phase compensation would have predictably generated or supported a solitonic pulse to preserve or stabilize the soliton condition and mitigate nonlinear phase-delay-induced signal loss.
Claim 13
With respect to claim 13, all limitations of claim 12 are taught by Gaudette, Honda, Lowery, Brener, Cornwell, Lockheed and Chraplyvy, except wherein claim 13 additionally expressly teaches that the solitonic pulse is generated using a Raman amplifier. However, within analogous art, Chraplyvy expressly teaches Raman amplification for soliton systems, and Brener teaches Raman amplification for reducing Kerr nonlinearities in optical transmission fiber.
For purposes of prior-art rejection only, and without withdrawing the above 35 U.S.C. § 112(b) rejection, claim 13 is interpreted as requiring use of a Raman amplifier to generate or support the solitonic pulse recited in claim 12.
Chraplyvy states: “It has been recognized for Some time that Raman amplification, in principle, offers a Solution. Postulated Soliton Systems have used the entire fiber as the Raman amplification medium, with pump injection points at 20-60 km Spacing to maintain Signal intensity sufficiently constant.” [Chraplyvy, col. 1, lines 24-30; p. 3].
Chraplyvy states: “Distributed Amplifier--In the context of Raman amplification, an amplifier constituted of all or a Substantial length of the transmission fiber itself. AS usually contemplated, the distributed amplification fiber is unmodified transmission fiber.” [Chraplyvy, col. 2, lines 42-47; p. 3].
Brener states: “The need remaining in the prior art is addressed by the present invention, which relates to an optical transmission system utilizing optical phase conjugation with included Raman amplification to reduce the presence of four-wave mixing and other Kerr effect nonlinearities in the transmission fiber.” [Brener, col. 2, lines 40-47; p. 2].
Brener states: “In accordance with the teachings of the present invention, the phase conjugation compensation is improved by inserting Raman gain in each fiber span... By providing this gain in the specified spans, four-waving mixing and other nonlinearities are significantly reduced.” [Brener, col. 2, lines 48-55; p. 2].
One of ordinary skill would have been motivated to use a Raman amplifier for the solitonic pulse of claim 12 because Chraplyvy expressly teaches that Raman amplification is a solution
for soliton systems and can maintain signal intensity sufficiently constant for pulse-shape preservation, while Brener teaches Raman gain in optical fiber spans to reduce Kerr nonlinearities. The use of a Raman amplifier to generate or support a solitonic pulse would have been a predictable application of known soliton/Raman amplification techniques in the same optical fiber transmission environment.
Claim 19
With respect to claim 19, all limitations of claim 14 are taught by Gaudette, Honda, Lowery and Brener, except wherein claim 19 additionally expressly teaches that the cause is SPM and dispersion cooperating to form a soliton and that the action comprises using a Raman amplifier to generate a solitonic pulse that balances the soliton. The same Raman-assisted soliton teachings of Chraplyvy and the same Kerr/Raman teachings of Brener apply to claim 19.
For purposes of prior-art rejection only, and without withdrawing the above 35 U.S.C. § 112(b) rejection, claim 19 is interpreted as requiring processor-executable instructions to use a Raman amplifier to generate or support a solitonic pulse so that the nonlinear SPM effect and dispersion are maintained in a condition that preserves or stabilizes the solitonic pulse shape during propagation.
Chraplyvy states: “Needs of Soliton Systems, which require operation within a critical intensity range to maintain pulse shape... are not easily satisfied with the EDFA. It has been recognized for Some time that Raman amplification, in principle, offers a Solution. Postulated Soliton Systems have used the entire fiber as the Raman amplification medium... to maintain Signal intensity sufficiently constant.” [Chraplyvy, col. 1, lines 18-30; p. 3].
Brener states: “These non-linearities are usually classified as four-wave mixing (FWM), self-phase modulation (SPM) and cross-phase modulation (XPM). For long distance communication over optical fiber, dispersion and nonlinearities must be controlled, compensated, or suppressed.” [Brener, col. 1, lines 58-63; p. 2].
Brener states: “As a result of the Raman amplification, the optical power along each separate span will be essentially “symmetric,” as shown in the optical power distribution graphs included in FIG. 6. Therefore, the performance of OPC 200 will be significantly improved and, in general, can now be used for spans of any length.” [Brener, col. 4, lines 56-65; p. 4].
One of ordinary skill would have been motivated to implement the Raman-assisted solitonic-pulse action in the processor-executable medium of claim 14 because the software/DSP operations already determine the nonlinear cause and initiate a mitigation action. Chraplyvy provides the known Raman-amplifier solution for soliton systems requiring constant intensity to maintain pulse shape, and Brener provides the known Raman-gain technique for reducing Kerr nonlinearities. Applying those teachings to the claim-14 computer-readable-medium implementation would have predictably caused the processor-executed method to initiate Raman-assisted solitonic pulse generation when the determined cause is SPM cooperating with dispersion.
Accordingly, claims 1-20 are rejected under 35 U.S.C. § 103. The cited references are all within the same field of optical fiber communication systems, WDM/DWDM optical networks, coherent optical processing, nonlinear fiber impairment estimation, launch-power/channel-spacing optimization, Raman amplification, soliton support, and dispersion/nonlinear compensation. The combination does not require a change in the principle of operation of any reference. Rather, the combination applies known coherent/DSP impairment measurement, known nonlinear phase compensation, known launch-power control, known channel-spacing control, known electronic dispersion compensation, and known Raman/soliton amplification techniques to the same problem of minimizing nonlinear phase-delay-induced signal loss in optical fiber.
It is noted that any citations to specific, pages, columns, lines, or figures in the prior art references and any interpretation of the reference should not be considered to be limiting in any way. A reference is relevant for all it contains and may be relied upon for all that it would have reasonably suggested to one having ordinary skill in the art. See MPEP 2123.
Conclusion
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/MOHAMMED ABDELRAHEEM/Examiner, Art Unit 2635
/DAVID C PAYNE/Supervisory Patent Examiner, Art Unit 2635
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