Polarization-insensitive wavelength conversion for polarization multiplexing non-return-to-zero quadrature phase shift keying signals based on four-wave mixing in a semiconductor optical amplifier using digital coherent detection

Abstract

We have theoretically and numerically investigated polarization-insensitive all-optical wavelength conversion for polarization multiplexing quadrature phase shift keying (QPSK) signals based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) with a polarization diversity and digital coherent detection. The simulation results show that the different frequency spacing between pumps and the signal have serious effects on the conversion efficiency, that there is an optimal SOA injection current by considering a high conversion efficiency and a small pattern effect, and that the pattern effect on polarization multiplexing QPSK signals is much lower than non-return-to-zero signals.