On the Performance of Digital Back Propagation in Spatial Multiplexing Systems

Nonlinear performance in spatial multiplexing systems is strongly determined by the interplay between differential mode delay, linear mode coupling, and Kerr nonlinearity. In this article we review and extend the analysis of different solution methods for the linear coupling operator in the coupled nonlinear Schrödinger equation for spatial multiplexed propagation. Numerical solution methods are compared for different operational regimes as determined by differential mode delay and linear mode coupling. Finally, we review and extend the study of digital methods to mitigate the Kerr nonlinearity for arbitrary levels of random linear mode coupling. For the first time, it is shown that in spatial multiplexing systems transmission performance can be improved by reducing the number of back propagated channels for non-negligible levels of differential mode delay.