A Study Of The Effects And Improvement Of FWM On DWDM

The technology of DWDM combined with EDFA can take fully advantage of capability of fibers, being a premium method of realizing high-capacity, long-haul, high-speed communications. For the long time, the attenuation, dispersion and nonlinearity of fibers are three major limitations to fiber communication systems. Because of using of EDFA, the attenuation of fibers was not an important transmission limitation. At the same time, dispersion managements and dispersion-supported techniques can be used to improve DWDM system performances. However, the undesired questions fiber nonlinear effects cause still don't crack. What's more, with the light power obviously intensifying and tunnel noticeably increasing, fiber nonlinearities have become a mainly important limitation imposing on systems. System specifications such as total transmission distance, amplifier spacing, the number of DWDM channels and the power per channel are all affected by the fiber nonlinear effects, especially FWM effects. Therefore, studying on nonlinear effects, especially FWM, exist has absolutely significant theoretical and practical meanings. It is expected to help augment fiber capacity and improve the communication quality.The dissertation studied the existed theories of FWM in the single mode fiber and simulated or improved and developed them. The detailed work of the dissertation as below: (1) Basic conceptions related to FWM, the origin of FWM, the effects of FWM on DWDM systems and some improvements are systematically introduced. (2) The objective of this thesis is to directly obtain the FWM transmission equation in DWDM systems by applying some useful hypothesis. This equation can completely describe FWM transmission actions under DWDM systems. It can be used to analyze the effect of FWM directly. (3) Applying the transmission model presented above, numerical value is calculated. At the same time, comparision of the effects of FWM on WDM transmission is made by Optisystem which can simulate the fiber transmission systems. The simulated results indicate that choosing reasonable EDFA span can minish FWM effects. The simulated results are compared with the results obtained in the theory model and the two results are identical.