An Algorithm Development of Impairment Stimulated Raman Scattering for Efficient Optical Communication System

Abstract

Abstract The nonlinear effects degrade the performance of system. Because nonlinear effects tend to manifest themselves when optical power is very high, there study became important in DWDM system. The nonlinearities in optical fibers fall into two categories. One is stimulated scattering (Raman and Brillouin), and the other is the optical Kerr effect which causes due to changes in the refractive index of fiber with optical power. Depending upon the type of input signal, kerr-non-linearity manifests itself in three different effects such as Self-Phase Modulation (SPM), Cross-Phase Modulation (CPM) and Four-Wave Mixing (FWM). At high power level, the inelastic scattering phenomenon can induce stimulated effects such as Stimulated Brillouin-Scattering (SBS) and Stimulated Raman-Scattering (SRS). The intensity of light grows exponentially if the incident power exceeds a certain threshold value. The difference between Brillouin and Raman scattering is that the Brillouin generated phonons (acoustic) are coherent and give rise to a macroscopic acoustic wave in fiber, while in Raman scattering the phonons (optical) are incoherent and no macroscopic wave is generated, SRS is much less of a problem than SBS. Its threshold is close to 1 Watt, nearly a thousand times higher than SBS. But real systems are being deployed with EDFAs having optical output powers of 500 mW (+27 dBm), and this will only go higher. A fiber optic link that includes three such optical amplifiers will reach this limit since the limit drops proportionally by the number of optical amplifiers in series. In this Dissertation stimulated Raman scattering modal has been study and presented a linear power division algorithm to achieve almost constant modulated SRS power. This assumes a linear variation of power in channel with respect to each other which is a result of experimental verification. During this study variation of signal power from 1 to 60 mW was done and number of channels varied from 3 to 99.