Interchannel nonlinearities in coherent polarization-division-multiplexed quadrature-phase-shift-keying systems

We study with simulations interchannel nonlinear effects on a 42.8-Gb/s coherent polarization-division-multiplexed quadrature-phase-shift-keying (PDM-QPSK) system with and without dispersion management. We find that interchannel cross-phase-modulation induced nonlinear polarization scattering can severely degrade the performance of a dispersion-managed PDM-QPSK system. We demonstrate that the time-interleaved return-to-zero PDM-QPSK, where the symbols of the two polarizations are shifted by half a symbol in time, can significantly suppress the nonlinear polarization scattering in dispersion managed systems, and make systems with inline dispersion-compensation fiber (DCF) achieve better performance than those without DCF. © 2009 IEEE.