NONLINEARITY CANCELLATION IN FIBER OPTIC TRANSMISSION BASED ON FREQUENCY-MUTUALLY-REFERENCED CARRIERS

• US 20170019178A1
• Filed: 02/24/2015
• Published: 01/19/2017
• Est. Priority Date: 02/24/2014
• Status: Abandoned Application

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: ALIC, Nikola, RADIC, Stojan
• Application Number:
  US15/121,346
• Publication Number:
  US 20170019178A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 10/2543 due to fibre non-linearities, e.g. Kerr effect
• CPC Class Codes: H04B 10/506 Multiwavelength transmitters
• CPC Class Codes: H04B 10/572 Wavelength control
• CPC Class Codes: H04B 10/6163 Compensation of non-linear effects in the fiber optic link, e.g. self-phase modulation [SPM], cross-phase modulation [XPM], four wave mixing [FWM]
• CPC Class Codes: H04B 10/697 Arrangements for reducing noise and distortion
• CPC Class Codes: H04B 2210/252 after the transmission line, i.e. post-compensation
• CPC Class Codes: H04B 2210/254 before the transmission line, i.e. pre-compensation
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0305 in end terminals
• CPC Class Codes: H04J 14/06 Polarisation multiplex systems
• CPC Class Codes: H04L 25/03006 Arrangements for removing intersymbol interference

Abstract

A system and method for mitigating nonlinearity in an optical communication link with multiple carriers uses mutual frequency referencing to stabilize at least a portion of the multiple carriers. Using at least one frequency-referenced signal, carrier nonlinearity can be determined and compensated within the link by pre-distortion, back-propagation, or a combination of both. Mutual frequency referencing may be performed at the emitting end of the link, at the receiving end, or a combination of both.

Claims

1. A method for mitigating nonlinearity in an optical communication link comprising multiple carriers, the method comprising:

applying mutual frequency referencing to at least a portion of the multiple carriers by one or more of frequency locking free running lasers, generating the multiple carriers using a frequency comb, and generating the multiple carriers using stabilized independent lasers;

using at least one frequency-referenced carrier, determining nonlinearity within the link; and

compensating for the determined nonlinearity, wherein compensating comprises canceling the nonlinearity by one or more of applying a pre-distortion to the carriers, applying back propagation, using a nonlinear equalizer, generating a feedback correction signal with a frequency-locked local oscillator, and applying calculated phase conjugation of a received signal.

2. The method of claim 1, wherein applying mutual frequency referencing is performed at a transmitting end of the link.

4. The method of claim 1, wherein applying mutual frequency referencing comprises applying frequency locking, and wherein frequency locking is selected from injection locking, current injection, laser cavity control, opto-electronic phase-locked loops, frequency-locked loops and cavity-based wavelength lockers.

7. The method of claim 1, wherein the independent lasers are locked in frequency to a frequency reference.

8. The method of claim 7, wherein the frequency reference is located at one of a receiving end and an emitting end of the link.

11. The method of claim 1, wherein applying a pre-distortion comprises generating a virtual link characterized by opposite sign physical constants and negative gain relative to the link.

15. The method of claim 1, wherein compensating comprises generating a feedback correction signal and wherein the frequency-locked local oscillator is selected from the group consisting of frequency comb, injection locking, current injection, laser cavity control, opto-electronic phase-locked loops, frequency-locked loops, and cavity-based wavelength locker.

17. The method of claim 1, wherein compensating comprises applying calculated phase conjugation, and wherein phase conjugation is implemented all-optically, electro-optically, or a combination thereof.

18. The method of claim 1, wherein applying mutual frequency referencing to at least a portion of the multiple carriers comprises defining subsets of neighboring carriers within the multiple carriers, wherein the carriers within each subset are mutually frequency locked.

19. The method of claim 18, wherein the subsets are at least partially overlapping.

20. The method of claim 19, wherein the subsets are defined by a sliding window.

21. The method of claim 1, wherein applying mutual frequency referencing is non-continuous.

3. (canceled)

5-6. -6. (canceled)

9-10. -10. (canceled)

12-14. -14. (canceled)

16. (canceled)

22. An optical fiber transmission system, the system comprising:

a carrier source configured for generating a plurality of channels, wherein the channels are configured for imprinting with information-containing waveforms, wherein the carrier source comprises one or more of a frequency comb, a frequency-referenced carrier source wherein the plurality of channels are at least partially mutually frequency locked, and independent stabilized lasers;

a multiplexer configured for receiving the plurality of channels and outputting a multiplexed signal;

one or more transmission links for transmitting the multiplexed signal, the transmission link comprising an optical fiber and an amplifier;

a demultiplexer configured for receiving an optical signal at a receiving end of the transmission link;

a plurality of receivers for receiving demultiplexed signals, each receiver configured for receiving one of the plurality of wavelengths; and

a processor for detecting nonlinearity within the transmission link and calculating compensation for substantially cancelling the nonlinearity;

wherein at least one of the carrier source and the plurality of receivers comprises a frequency-referenced oscillator.

23. The system of claim 22, wherein the frequency-referenced oscillator is stabilized by one or more of injection locking, current injection, laser cavity control, opto-electronic phase-locked loops, frequency-locked loops and cavity-based wavelength lockers.

25. The system of claim 22, wherein a least a portion of the plurality of channels comprises subsets of neighboring channels, wherein the channels within each subset are mutually frequency locked.

27. The system of claim 22, further comprising a pre-distortion processor configured for providing input to the carrier source.

28. The system of claim 27, wherein the pre-distortion processor generates a virtual link characterized by opposite sign physical constants and negative gain relative to the transmission link.

29. The system of claim 22, wherein the plurality of receivers comprise frequency-locked local oscillators, and wherein the processor comprises a back-propagation block.

30. The system of claim 22, wherein the optical fiber comprises one or more fiber selected from the group consisting of single mode fiber, multi-mode fiber, and multi-core fiber.

31. The system of claim 30, wherein the system is a polarization multiplexed system.

24. (canceled)

26. (canceled)