Study Into The Impact Of SRS On The Performances Of DWDM Fiber Communication Systems

With the enlargement of communication capacity, the channel number of DenseWavelength Division Multiplexed (DWDM) is increasing, input power in fiber is enhanced,the performance of the communication systems might be degraded by non-linearity in theoptical fiber. In the thesis the major object will center on studying that the impacts onperformance of the communication system due to the nonlinear effect of Stimulated RamanScattering (SRS), in which included are resulting in power transference from shorterwavelength channels to longer wavelength channels;making SRS cross-talk;causing thefluctuating of output power;producing error codes and degrading the performance ofDWDM systems. In the paper, by using mathematic and engineering methods we presented aclear in physical meaning and simple in practice model, which is referred as 'time-domainsplit-step method', to calculate the coupling effects of SRS with optical fiber dispersion,thereby we provided a successful way for overcoming the difficulty without analyticalsolution in this problem. Our model is valid for any arbitrary fiber dispersion parameter,input power distribution, independently of transmission distance, channel number andunequal channel spacing. Based on the model, the transmission powers, average powers, thestandard deviation of output power, SRS cross-talk and SRS signal noise ratio of all channelsare calculated respectively;the mechanism reducing the effects of SRS by optical fiberdispersion is analyzed. We use the time-domain split-step method to investigate the statisticalcharacteristics of SRS. The mean and the standard deviation of transmission powers of allchannels are derived analytically in a closed-form formula for WDM systems with SRS andinteger bits dispersion walk-off. The probability density function (PDF) of output powers ofall channels is confirmed to be Gaussian distribution. The numerical results show a goodcorrespondence with analytical formulae. SRS-induced bit-error rate and signal noise ratio ofWDM communication systems are predicted theoretically. The article has reported a generalinvestigation on the effect of SRS to the performances of DWDM communication systems.