目前，光纤通信正向着长距离、大容量、高速率的趋势发展，而光纤中的非线性效应特别是克尔效应，即FWM效应、SPM效应和XPM效应，会对系统产生不利影响。在DWDM系统中，随着信道间隔的减小以及入纤功率的提高，克尔效应对系统的影响也随之加重。因此，对XPM效应、SPM效应和FWM效应的研究变得至关重要。 本文主要研究了FWM效应产生的机理及其对DWDM系统性能的影响，以及抑制FWM效应的方法。采用Matlab软件和Optisystem软件相结合，通过实验研究了三种色散补偿方式、不同信号调制格式和不同入纤功率与FWM效应之间的关系；实验结果表明，后置色散补偿方式、RZ以及合适的入纤功率有助于抑制FWM效应，减小系统误码率，提高系统性能。 本文对SPM效应和XPM效应的产生进行理论分析，介绍了二者对DWDM系统性能的影响。使用软件在实验中探究了影响SPM效应的两大因素，即相移和色散；同时，通过实验研究了不同入纤功率和传输速率对XPM效应的影响。实验结果表明，合理的色散补偿及在反常色散介质中，SPM效应导致的频谱展宽能得到有效抑制；传输速率越小XPM效应越小，当速率不变时，在一定限度内，较高的入纤功率能减小XPM效应，提高DWDM系统的通信质量

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 affected the optical communication system increasingly, such as four-wave mixing(FWM), self-phase modulation and cross-phase modulation(XPM). In the dense-wavelength division multiplexing(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 to study on FWM,SPM and XPM. This paper mainly studied the FWM generation mechanism, its effects on DWDM system and the methods of inhibiting FWM effect. By using Optisystem software and Matlab software, we studied the relationship between FWM effects and three dispersion compensation, different signal modulation formats and input power. Experimental results show that the rear dispersion compensation mode, return-to-zero (RZ) code and proper input power can help to restrain the FWM 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 two main factors influence SPM, namely phase shift and dispersion by the usage of software; and study the influence of different input power and transmission rate on XPM. The experimental results show that the spectrum broadening caused by SPM can be effectively restrain by means of proper dispersion compensation as well as in anomalous dispersion medium. The smaller the 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 the communication quality of DWDM system.