Research On Kerr Effect In High-speed Long-distance DWDM System

As the optical communication system developing in the direction of the long distance,large capacity, high rate, the optical nonlinear effects, especially the Kerr effect, have affectedthe optical communication system increasingly, such as four-wave mixing(FWM), self-phasemodulation and cross-phase modulation(XPM). In the dense-wavelength divisionmultiplexing(DWDM) system, the smaller of channel spacing and the higher of input power,the influence of Kerr effect on the system is more serious. Thus, it is of great importance tostudy on FWM,SPM and XPM.This paper mainly studied the FWM generation mechanism, its effects on DWDM systemand the methods of inhibiting FWM effect. By using Optisystem software and Matlab software,we studied the relationship between FWM effects and three dispersion compensation, differentsignal modulation formats and input power. Experimental results show that the rear dispersioncompensation mode, return-to-zero (RZ) code and proper input power can help to restrain theFWM effect, as well as reducing the system error rate and improving system performance.In this paper, we analyze the generation of SPM and XPM theoretically, at the same time,introduce their effects on the performance of DWDM system. Experiment investigate the twomain factors influence SPM, namely phase shift and dispersion by the usage of software; andstudy the influence of different input power and transmission rate on XPM. The experimentalresults show that the spectrum broadening caused by SPM can be effectively restrain by meansof proper dispersion compensation as well as in anomalous dispersion medium. The smallerthe transmission rate, the smaller the XPM effect. When the transmission rate is constant,higher input power within certain limits can decrease the XPM effect and optimize thecommunication quality of DWDM system.