Look-up table and digital transmitter based architecture for fiber nonlinearity compensation

1. A method to process an optical signal, comprising:

generating a symbol pattern in accordance with predetermined rules;

pre-processing the symbol pattern with non-linearity compensation to fill a look-up table in an off-line mode by applying transmission channel information including span length, fiber type, and dispersion coefficients to combinations of multiple-channel input symbol patterns for a single polarization and PolMux coefficients to generate one dimensional symbol patterns in the look-up table;

applying said predetermined rules to channel input data for phase modulation compensation to generate a real-time symbol pattern during an on-line mode;

indexing the look-up table with the real-time symbol pattern to locate a non-linearity compensation output; and

modulating the optical signal with the compensation output.

2. The method of claim 1 , comprising applying the modulated optical signal to a digital-to-analog converter.

3. The method of claim 1 , wherein generating the look-up table comprises:

determining a plurality of combination of the input symbol sequences from multiple channels

performing non-linearity processing on the symbol pattern and storing the pattern in the lookup table.

4. The method of claim 1 , wherein the non-linearity compensation comprises back-propagation.

5. The method of claim 1 , wherein the input symbol patterns indicate modulation format and transmitter architecture.

6. The method of claim 1 , wherein the input symbol patterns include single polarization or polarization multiplexing (PoIMux) patterns.

7. The method of claim 1 , comprising reorganizing the input symbol patterns to generate a one dimensional symbol pattern searchable in a look-up table.

8. The method of claim 7 , comprising performing non-linearity compensation on the input symbol patterns and saving results in the look-up table.

9. The method of claim 8 , comprising performing non-linearity compensation at a digital transmitter side to ensure availability of error-free original data for processing and search the look-up table.

10. The method of claim 1 , wherein the symbol pattern comprises a one-dimensional symbol pattern or a multi-dimensional symbol pattern.

11. An apparatus to process an optical signal, comprising:

a pre-processor to populate a non-linearity compensation data structure based on a set of predetermined rules in a non-real-time off-line mode, wherein the pre-processor receives transmission channel information including span length, fiber type, and dispersion coefficients, and applies combinations of multiple-channel input symbol patterns for a single polarization and PolMux coefficients to store one dimensional symbol patterns in the non-linearity compensation data structure; and

an amplifier applying said predetermined rules in real-time to one or more channel input data using the data structure to determine a non-linearity compensation output.

12. The apparatus of claim 11 , wherein the amplifier comprises a single polarization transmitter.

13. The apparatus of claim 11 , wherein the amplifier comprises a PolMux transmitter.

14. The apparatus of claim 11 , comprising an array of digital to analog converters (DACs) coupled to the amplifier.

15. The apparatus of claim 14 , comprising an array of in-phase/quadrature (I/Q) modulators coupled to the DACs.

16. The apparatus of claim 15 , comprising:

a laser; and

a coupler provide CW light source to the I/Q modulators.

17. The apparatus of claim 11 , wherein the data structure comprises a look-up table, and wherein the look-up table is generated by determining a plurality of combination of the input symbol sequences from multiple channels and performing non-linearity processing on the symbol pattern and storing the pattern in the look-up table.

18. The apparatus of claim 11 , wherein the non-linearity compensation comprises backpropagation.

19. The apparatus of claim 11 , wherein the input symbol patterns relate to modulation format and transmitter architecture.

20. The apparatus of claim 11 , wherein the input symbol patterns include single polarization or polarization multiplexing (PoIMux) patterns.

21. The apparatus of claim 11 , comprising an analog to digital converter {A DC) to perform twotimes up-sampling of the optical signal by repeating the optical signal twice.

22. The apparatus of claim 11 , comprising a modulator coupled to the amplifier to modulate the optical signal with the compensation output.