Impact of Inter-Channel Nonlinearities on 10-Gbaud NRZ-DQPSK WDM Transmission over Raman Amplified NZDSF Spans

We show that inter-channel cross-phase modulation (XPM) significantly reduces the performance of a 10-Gbaud differential-quadrature-phase-shift-keying (DQPSK) WDM transmission system, and nonlinear polarization scattering causes further performance degradation when polarization division multiplexing is applied.