A parametric gain approach to performance evaluation of DPSK/DQPSK systems with nonlinear phase noise

Abstract

We present a novel method based on parametric gain (PG) to study the impact of nonlinear phase noise in dispersion-managed differentially phase-modulated optical transmission systems. By linearizing the interaction of signal and noise, the received ASE is approximated as a stationary Gaussian process, whose statistics are found by using a low-pass filtered version of the modulating signal. The BER is then evaluated by adapting standard methods for quadratic detectors, for single-channel binary and quaternary PSK systems, both for NRZ and RZ supporting pulses. We show that in the RZ case parametric gain causes a larger penalty than in the NRZ case, and that DQPSK is less robust to PG than DPSK. © 2005 Springer Science + Business Media, Inc. Boston.