直接检测光正交频分复用系统一阶偏振模色散研究

Impact of First-order PMD in Direct Detection Optical Orthogonal Frequency Division Multiplexing System

基于直接检测的光OFDM系统(DDO-OFDM),实现简单、成本较低,对未来高速光传输具有重要的借鉴价值。而在高速传输中,偏振效应带来OFDM信号展宽及输出偏振态的不同,严重影响系统传输性能。对DDO-OFDM系统中的一阶偏振模色散(PMD)作用机理和数学模型进行分析,结果表明,DDO-OFDM系统中一阶PMD仅对OFDM信号子载波信号幅度附加余弦因子,通过信道均衡,可有效去除此噪声影响,差分群时延为50ps条件下,以10Gb/s的速率在单模光纤传输800km,DDO-OFDM系统Q值为16dB,较色度色散影响下系统性能仅有0.3dB降低。

Direct detection optical OFDM （DDO-OFDM） is being considered as a promising technology for future long-haul optical transmission because of its computation efficiency and lower cost. However, polarization mode dispersion （PMD） influences system performance seri- ously in high speed transmission. In the letter, the mathematical model and effect on the trans- mission system is emphatically analyzed in DDO-OFDM system based on first-order PDM. With analysis and simulation, it is shown that first-order PMD adds cosine factors for different OFDM sub-carriers, which could he eliminated by channel equalization. The system Q is about 16dB for 800km distance and speed of 10Gbit/s transmission through standard--single--mode fiber with differential group delay （DGD） of 50ps, a 0.3dB of decrease in performance influenced by chro- matic dispersion.