文章对长距离传输系统中使用的码型(改进型光双二进制归零码MD -RZ和光双二进制非归零码MD -NRZ)进行了比较。仿真结果表明: 长距离传输时, 采用色散补偿技术, MD -RZ信号相对于MD -NRZ信号有更低的误码率和更高的接收机灵敏度。文章还提出了一种使用保偏光纤环路镜像器(PMFLM)产生MD -RZ信号的方法, 并在理论上证明了这种全光方法的可行性。

This paper makes comparisons between the modified optical duobinary return-to-zero (MD -RZ) format and the optical duobinary non return-to-zero (MD -NRZ) format, which are both used in long distance transmission systems. Simulation results show that MD -RZ signals have lower BER and higher receiver sensibility than MD -NRZ signals by using the dispersion compensation technology. In addition, it presents a nove1 all-optical method for the generation of MD -RZ signals by using a Polarization Maintaining Fiber Loop Mirror (PMFLM) and theoretically proves its feasibility.