System and methods for adaptive equalization for optical modulation formats

A system, comprising:

• a receiver for receiving a carrier wave comprising a first polarization state and a second polarization state, wherein a correlation exists between the first polarization state and the second polarization state;
• an adaptive equalizer for:
• generating a first constellation corresponding to the first polarization state and a second constellation corresponding to the second polarization state;
• equalizing a first output based on a first signal associated with the first polarization state and a second output based on a second signal associated with the second polarization state;
• a processor;
• and
• a memory to store computer program instructions, the computer program instructions when executed on the processor cause the processor to perform operations comprising:
• calculating a first expected value based on the first constellation and a second expected value based on the second constellation;
• calculating a first error based on a difference between the first expected value and the first output, the first expected value being constrained based on the first output and the second output;
• calculating a second error based on a difference between the second expected value and the second output, the second expected value being constrained based on the first output and the second output;
• and
• generating a feedback signal based on the first error, the second error and the correlation;
• the adaptive equalizer further for determining coefficients for filters of the adaptive equalizer using the feedback signal.

A non-transitory computer readable medium storing computer program instructions for processing a carrier wave to provide feedback to an adaptive equalizer, the carrier wave comprising a first polarization state and a second polarization state, wherein a correlation exists between the first polarization state and the second polarization state, the computer program instructions, when executed on a processor, cause the processor to perform operations comprising:

• calculating a first expected value based on a first constellation corresponding to the first polarization state and a second expected value based on a second constellation corresponding to the second polarization state;
• calculating a first error based on a difference between the first expected value and a first output, the first output being generated by equalizing a first signal associated with the first polarization state, the first expected value being constrained based on the first output and the second output;
• calculating a second error based on a difference between the second expected value and a second output, the second output being generated by equalizing a second signal associated with the second polarization state, the second expected value being constrained based on the first output and the second output;
• generating a feedback signal based on the first error, the second error and the correlation;
• and
• transmitting the feedback signal to the adaptive equalizer for determining coefficients for filters of the adaptive equalizer.