Mitigation of intra-channel nonlinearities using a frequency-domain Volterra series equalizer.

TLDR: A frequency-domain Volterra series nonlinear equalizer is applied to a 20 Gbaud NRZ-QPSK signal propagated over 1600 km and a 2 dB improvement on the nonlinear tolerance over backward propagation split-step Fourier method is obtained.

Abstract: We address the issue of intra-channel nonlinear compensation using a Volterra series nonlinear equalizer based on an analytical closed-form solution for the 3rd order Volterra kernel in frequency-domain The performance of the method is investigated through numerical simulations for a single-channel optical system using a 20 Gbaud NRZ-QPSK test signal propagated over 1600 km of both standard single-mode fiber and non-zero dispersion shifted fiber We carry on performance and computational effort comparisons with the well-known backward propagation split-step Fourier (BP-SSF) method The alias-free frequency-domain implementation of the Volterra series nonlinear equalizer makes it an attractive approach to work at low sampling rates, enabling to surpass the maximum performance of BP-SSF at 2× oversampling Linear and nonlinear equalization can be treated independently, providing more flexibility to the equalization subsystem The parallel structure of the algorithm is also a key advantage in terms of real-time implementation