Experimental demonstration of intra-channel nonlinearity mitigation in coherent QPSK systems with nonlinear electrical equaliser

The mitigation of intra-channel nonlinearities in 10 Gbaud coherent NRZ-QPSK systems via a nonlinear electrical equaliser based on Volterra theory is experimentally demonstrated. Without the requirement of prior knowledge of the fibre link, the equaliser significantly improves the system performance compared to digital dispersion compensation only.