总结了多模光纤用于数据通信的优劣点,并分析多模光纤在未来高速大容量长距离无源光接入网(PON)中应用的可行性。从弱导光纤波导理论出发,忽略模内色散以及非线性效应的影响,建立多模光纤的简化模型,并在该简化多模光纤模型的基础上,采用仿真实验的方式,对一些改善多模光纤传输性能的技术:偏心注入,改变模斑尺寸,环形注入以及判决反馈均衡进行了分析,研究和比较。实验结果证明,采用模斑整形(主要是环形注入)与反馈均衡结合的方式可以有效地改善多模光纤的传输性能,使得10 Gb/s信号在多模光纤中传输超过1 km。

The feasibility for the applying of multimode fiber (MMF) in the future long haul,high bit-rate,and large capacity PON is analyzed,and the strengths and weakness of MMF are summarized.Then,initiating from the waveguide theory in the weakly guiding fiber and neglecting the intra-modal dispersion as well as nonlinearity,a simple model for multimode fiber is built,based on which analysis,research and comparison through simulation experiments on some performance improving techniques of MMF are made:offset launching,mode size changing,ring launching and feedback equalization.The simulation results demonstrated that the combination of field shaping (mainly ring launching) and feedback equalization can obviously improve the transmission properties of MMF,because of which,the 10 Gb/s data can travel in the MMF for more than 1 km.