Inter-Channel Nonlinearities in Coherent Polarization-Division-Multiplexed Quadrature-Phase-Shift-Keying Systems
01 January 2009
We study inter-channel 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 inter-channel cross-phase modulation (XPM) 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 (RZ) 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.