The limitation of initial chirp and higher-order PMD to 40 G bit/s optical transmission systems

The performance degradation due to the combined effects of initial chirp and higher-order polarization mode dispersion (PMD) in a 40 G bit/s non-return-zero (NRZ) optical fiber transmission system with first-order PMD compensation is numerically simulated by Monte Carlo analysis method. All order PMD are considered by modeling an optical fiber as a number of concatenated small fiber segments. Simulation results show that the eye opening penalty (EOP) still can reach about 2 dB with outage probability of 10^-5 (about 5 minutes per year) for a PMD value of 6 ps after the first-order PMD has been compensated for. It has also been proven by simulation that there exists interaction between the pure initial chirp and higher-order PMD. Due to the higher-order PMD, initial chirps always bring extra system penalty for both cases with or without the first-order PMD compensation, and EOP increases more sharply with initial chirp after the first-order PMD has been compensated for. For certain fixed PMD value, the larger the initial chirp (absolute value), the severer the system performance is degraded.