Design of feedforward master-slave carrier phase recovery in frequency comb-based superchannel coherent transmission systems with nonlinear phase noise

摘要

Master-slave common carrier phase recovery (MS-CCPR) is a method for reducing computational complexity of the phase recovery in mull-channel systems where the channels have correlated phase noise. However, these systems will suffer performance penalties if there are phase-noise differences between the channels. Since MS-CCPR schemes rely on phases of the subchannels being same, the intra-channel phase-drift will inevitably influence the design and performance of such schemes. In addition, fiber nonlinearities may introduce further different phase perturbations on the subchannels of a superchannel. This paper presents a master-slave carrier recovery method with compensation of the phase-noise differences based on the blind phase search method for optical frequency comb-based WDM systems. Specifically, we investigated in details using simulations, for the first time, the impact of this phase-noise differences on the performance of master-slave scheme in long-haul transmission systems with laser and nonlinear phase noise effects. In the MS-CCPR strategy used, the slave subchannels are preprocessed with the master-slave scheme, then a low-complexity slave phase-tracker is used to correct the phase-noise differences remaining on them. The concept has been numerically verified in simulations for square 16-QAM format, where the BER limit for soft-decision FEC could still be achieved in a link of 3000 km.