Equalization of non-linear optical channels

This paper presents a comparative analysis of various linear and nonlinear equalizers for a high density optical channel. Since the read-out process is nonlinear, a suitable model basedon the Volterra series has been adopted. In this work, we compare the performance and complexity of equalizers designed for linear and nonlinear channels. Specifically, Adaptive Minimum Mean Square Error (MSE), Adaptive Decision Feedback Equalizer (DFE), Nonlinear Adaptive Volterra Equalizer (NAVE) and Nonlinear Adaptive Decision Feedback Equalizer (NDFE) are analyzed, along with the Maximum Likelihood Sequence Estimator (MLSE), which is considered as a reference, Simulations show that the performance of classical structures (MSE, DFE, MLSE) is significantly reduced by the nonlinear response and that NAVE and NDFE achieve performance close to MLSE, with lower complexity.