# US 2026/0081682 A1 · Minimizing phase-delay-induced signal loss in optical fibers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2026/0081682 A1 - Document ID: US20260081682A1 - Status: Published application - Kind: A1 - Application number: 18/890,737 - Filed: 2024-09-19 - Published: 2026-03-19 - Earliest claimed: 2024-09-19 - Assignees: AT&T Communications Services India Private Limited - Applicants: AT&T Communications Services India Private Limited - Inventors: Mritunjay Pandey - Web page: https://patentgrep.com/patent/US20260081682A1 ## CPC - H04B 10/0793: {Network aspects, e.g. central monitoring of transmission parameters} - H04B 10/2543: due to fibre non-linearities, e.g. Kerr effect - H04B 10/255: Self-phase modulation [SPM] - H04B 10/2557: Cross-phase modulation [XPM] - H04B 10/2563: Four-wave mixing [FWM] - H04J 14/0221: {Power control, e.g. to keep the total optical power constant} - H04B: TRANSMISSION - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) ## Abstract A method includes calculating a phase of a light pulse that is propagating along an optical fiber of a fiber broadband communications network, calculating a change in the phase of the light pulse due to a nonlinearity, determining a cause of a portion of the change in the phase, wherein the cause is at least one of: a self-phase modulation, a cross-phase modulation, or a four-wave mixing, and initiating at least one action to mitigate the nonlinearity, wherein the at least one action is selected based on the cause that is determined. ## Claims ### Claim 1 A method comprising: 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; calculating, by the processing system, a change in the phase of the light pulse due to a nonlinearity; determining, by the processing system, a cause of a portion of the change in the phase, wherein the cause is at least one of: a self-phase modulation, a cross-phase modulation, or a four-wave mixing; and initiating, by the processing system, at least one action to mitigate the nonlinearity, wherein the at least one action is selected based on the cause that is determined. ### Claim 2 (depends on 1) The method of claim 1, wherein the calculating the phase of the light pulse is performed using a transponder pulse. ### Claim 3 (depends on 1) The method of claim 1, wherein the cause is the self-phase modulation, and the at least one action comprises: applying, by the processing system, a phase rotator to mitigate the self-phase modulation. ### Claim 4 (depends on 3) The method of claim 3, wherein the at least one action further comprises reducing a launch power of the light pulse simultaneously with the applying the phase rotator. ### Claim 5 (depends on 4) The method of claim 4, wherein the launch power is reduced to a power that balances a mitigation of the self-phase modulation with a minimization of amplified spontaneous emissions. ### Claim 6 (depends on 1) The method of claim 1, wherein the cause is the cross-phase modulation, and the at least one action comprises: applying, by the processing system, a phase rotator to mitigate the cross-phase modulation. ### Claim 7 (depends on 6) The method of claim 6, wherein the at least one action further comprises reducing a launch power of the light pulse simultaneously with the applying the phase rotator. ### Claim 8 (depends on 7) The method of claim 7, wherein the launch power is reduced to a power that balances a mitigation of the cross-phase modulation with a minimization of amplified spontaneous emissions. ### Claim 9 (depends on 1) The method of claim 1, wherein the cause is the four-wave mixing, and the at least one action comprises adjusting a spacing between adjacent channels of the optical fiber. ### Claim 10 (depends on 1) The method of claim 1, wherein the cause is the cross-phase modulation, and the at least one action comprises adjusting a spacing between adjacent channels of the optical fiber. ### Claim 11 (depends on 1) The method of claim 1, further comprising: applying, by the processing system, an electronic dispersion compensation to mitigate a dispersion of the light pulse. ### Claim 12 (depends on 1) The method of claim 1, wherein 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. ### Claim 13 (depends on 12) The method of claim 12, wherein the solitonic pulse is generated using a Raman amplifier. ### Claim 14 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 operations, the operations comprising: calculating a phase of a light pulse that is propagating along an optical fiber of a fiber broadband communications network; calculating a change in the phase of the light pulse due to a nonlinearity; determining a cause of a portion of the change in the phase, wherein the cause is at least one of: a self-phase modulation, a cross-phase modulation, or a four-wave mixing; and initiating at least one action to mitigate the nonlinearity, wherein the at least one action is selected based on the cause that is determined. ### Claim 15 (depends on 14) The non-transitory computer-readable medium of claim 14, wherein the cause is at least one of: the self-phase modulation or the cross-phase modulation, and the at least one action comprises: applying a phase rotator to mitigate the self-phase modulation or the cross-phase modulation. ### Claim 16 (depends on 15) The non-transitory computer-readable medium of claim 15, wherein the at least one action further comprises reducing a launch power of the light pulse simultaneously with the applying the phase rotator. ### Claim 17 (depends on 16) The non-transitory computer-readable medium of claim 16, wherein the launch power is reduced to a power that balances a mitigation of the self-phase modulation with a minimization of amplified spontaneous emissions. ### Claim 18 (depends on 14) The non-transitory computer-readable medium of claim 14, wherein the cause is at least one of: the cross-phase modulation or the four-wave mixing, and the at least one action comprises adjusting a spacing between adjacent channels of the optical fiber. ### Claim 19 (depends on 14) The non-transitory computer-readable medium of claim 14, wherein 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. ### Claim 20 An apparatus comprising: a processor; and a non-transitory computer-readable medium storing instructions which, when executed by the processor, cause the processor to perform operations, the operations comprising: calculating a phase of a light pulse that is propagating along an optical fiber of a fiber broadband communications network; calculating a change in the phase of the light pulse due to a nonlinearity; determining a cause of a portion of the change in the phase, wherein the cause is at least one of: a self-phase modulation, a cross-phase modulation, or a four-wave mixing; and initiating at least one action to mitigate the nonlinearity, wherein the at least one action is selected based on the cause that is determined.