Phase correction in high speed coherent optical communication

1. A method for phase correction, the method comprises:

generating in parallel and by a set of phase error detectors, a set of phase error detection results (PEDRs) related to a set of blocks of digital samples, the digital samples are frequency corrected and represent optical signals conveyed over a coherent optical communication link; wherein the PEDs introduce PED noise that is indifferent to phase errors of the set of the blocks of digital samples;

sending, in a sequential manner, the set of PEDRs, to a loop that comprises a loop filter;

generating, by the loop, phase difference results, wherein each phase difference result is indicative of a phase difference between a certain PEDR of the PEDRs and a loop filtered PEDR generated by filtering a PEDR that precedes the certain PEDR;

processing, by a phase correction unit, the digital samples and the phase different results, to provide phase corrected digital samples.

2. The method according to claim 1 wherein the loop consists essentially of the loop filter, a delay unit, and a subtraction unit; and wherein a generating of a phase difference result related to a PEDR comprises generating a subtraction result by subtracting the PEDR from a previous loop filtered PEDR, and applying a residue operation on the subtraction result.

3. The method according to claim 2 wherein for each PEDR of the set of PEDRs, the previous loop filtered PEDR is an outcome of filtering of a last PEDR before the PEDR.

4. The method according to claim 2 wherein the delay unit has a delay that equals a duration of a block of digital signals.

5. The method according to claim 1 wherein the generating, by the loop, of the phase difference results is executed without phase rotation.

6. A phase correction unit for phase correction, the phase correction unit comprises:

a set of phase error detectors that are configured to generate in parallel, a set of phase error detection results (PEDRs) related to a set of blocks of digital samples, the digital samples are frequency corrected and represent optical signals conveyed over a coherent optical communication link; wherein the PEDs introduce PED noise that is indifferent to phase errors of the set of the blocks of digital samples;

a loop that is configured to:

receive in a sequential manner, the set of PEDRs; the loop comprises a loop filter; and

generate phase difference results, wherein each phase difference result is indicative of a phase difference between a certain PEDR of the PEDRs and a loop filtered PEDR generated by filtering a PEDR that precedes the certain PEDR;

and a phase correction unit that is configured to process the digital samples and the phase different results, to provide phase corrected digital samples.

7. The phase correction unit according to claim 6 wherein the loop consists essentially of the loop filter, a delay unit, and a subtraction unit; and wherein a generating of a phase difference result related to a PEDR comprises generating a subtraction result by subtracting the PEDR from a previous loop filtered PEDR, and applying a residue operation on the subtraction result.

8. The phase correction unit according to claim 7 wherein for each PEDR of the set of PEDRs, the previous loop filtered PEDR is an outcome of filtering of a last PEDR before the PEDR.

9. The phase correction unit according to claim 7 wherein the delay unit has a delay that equals a duration of a block of digital signals.

10. The phase correction unit according to claim 6 configured to generate the phase difference results without phase rotation.