Performance comparison for NRZ, RZ and CSRZ modulation formats in ultralong-haul DWDM system

Transmission performances of 10Gbps DWDM NRZ, RZ and CSRZ system are compared by both theoretical simulation and experiment. Simulation shows the NRZ, RZ and CSRZ have different duty cycle, spectrum and chirp characteristics, which are the main reasons for different transmission performances. Simulation also shows that NRZ has the largest dispersion tolerance. The chirp of RZ brings out more jitter than the other two modulation formats do during transmission. CSRZ has less pulse distortion induced from dispersion due to its chirp characteristics. Our simulation is verified by experiments with a multi-channel 10Gbps ultra long haul system. The experiments of our transmission system show that both NRZ and RZ system can transmit above 3200km, and CSRZ can transmit as far as 5490km.