Performance limitations of an optical RZ-DPSK transmission system affected by frequency chirp, chromatic dispersion and polarization mode dispersion

The performance limitations due to the combined effects of frequency chirp and CD or PMD in a 40 Gbit/s optical Return-to-Zero Differential Phase-Shift-Keying (RZ-DPSK) transmission system are numerically simulated. By means of numerical simulations, we optimize the bandwidths of the optical and electrical receiver´s filters. Then, the impact of the Chirp factor (C) on the Bit Error Rate (BER) performance is analyzed when the received signal is filtered by two types of optical filter (Fabry-Perot filter (FP) or Fiber Bragg Grating filter (FBG)). The optical power penalties caused by the Frequency Chirp impact at BER of 10^-9 in the presence of CD or PMD are evaluated. Simulation results show that, without CD and PMD the system suffer a significant amount of power penalties due to the Chirp factor, and the optical filter has no influence on the power penalties. However, it is found that with CD or PMD, the optical filter has significant influence on the power penalty, and with CD the system which uses FBG filter always performs better than the one which uses FP filter, whereas with PMD the better performances switch from FBG filter to FP filter. This provides the basis for tradeoff between FP and FBG filter performances through careful selection of a suitable optical filter to high speed optical transmission system.