Correlated Nonlinear Phase-Noise in Multi-Subcarrier Systems: Modeling and Mitigation

In multi-subcarrier wavelength-division-multiplexed (WDM) systems, spectrally close subcarriers are influenced by nonlinearity in a similar way. This causes the nonlinear interference noise (NLIN) that affects them to be correlated - a fact that can be exploited for nonlinearity mitigation. Focusing on the effect of nonlinearity-induced phase noise (NLPN), we find the auto-correlation and cross-correlation functions of the NLPN influencing different subcarriers, and propose a mitigation algorithm that takes advantage of these correlations so as to improve the overall system performance. We validate our results numerically and experimentally.