Numerical simulation of the SPM penalty in a 10-Gb/s RZ-DPSK system

The impact of self-phase modulation-induced nonlinear phase noise in a 10-Gb/s return-to-zero differential phase-shift keying system is studied by numerical simulation. We show that the simple differential phase Q method based on the Gaussian approximation for the phase noise provides a relatively good estimate of the nonlinear penalty.