Effect Wavelength Division Multiplexed Optical Fiber Transmission Systems Performance Of The Research

The technology of WDM 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 WDM 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 WDM channels and the power per channel are all affected by the fiber nonlinear effects. Therefore, studying on electromagnetic fields traveling in single mode fibers where attenuations, dispersions and nonlinear effects exist has absolutely significant theoretical and practical meanings. It is expected to help augment fiber capacity and improve the communication quality.The objective of this thesis is to directly obtain the nonlinear transmission equation that governs propagation of optical pulses in single fibers, only employing field temporal-spatial Fourier transform. This equation can completely describe light pulse transmission actions under numerous circumstances including the fiber dispersion, attenuation and nonlinearity, and even the polarization state of light. Detailed analyses are carried to dig up this result, beginning with Maxwell's equations and some important concepts and using reasonable assumptions in real and actual fibers. It is found that the resultant NLSE can be applied into WDM fibercommunication systems conveniently to research and evaluate nonlinear effects on system performances and thus to provide the important theoretical foundation for real system designs.Then, the thesis continues to deal with the cause, character and effect on WDM systems of some kinds of nonlinearities, such as SPM, XPM, FWM, SRS and SBS, with the emphasis on multi-tunnel nonlinear effects (XPM, FWM and SRS). Some more reasonable modes for study and various techniques and suggestions to reduce the impairment effects are also provided and discussed. The analysis and conclusions of this thesis are definitely helpful for system designer to maximize the system performances.