Digital Post-Compensation of Nonlinear Distortions in Wavelength Conversion Based on Four-Wave Mixing in a Semiconductor Optical Amplifier

We present a novel low-complexity digital filter-based backpropagation (DFBP) technique to compensate the nonlinear distortions induced by a wavelength converter based on four-wave mixing in a semiconductor optical amplifier. We first develop the DFBP based on a small-signal approximation and probe performance via numerical simulations. We also experimentally demonstrate that application of DFBP to wavelength conversion of 10 Gbaud 16-QAM and 5 Gbaud 64-QAM signals significantly improves the error-vector magnitude and the bit error rate when the wavelength converted signal is limited by the nonlinear distortions.