Study On The Dispersion Of Fiber Raman Amplifier By TDM Pumping

With the rapid development of fiber communication,a large capacity,long distance and ultra-high-speed communication system has become a bottleneck of it.The signal is affected by optical fiber loss,dispersion and various nonlinear effects during transmission.The crosstalk and deformation of signals caused by fiber loss can be solved by FRA(fiber Raman amplifier).Therefore,the interference and broadening caused by dispersion has become the main factors to limit the optical fiber communication.The multiwave TDM(time division multiplexing)-pumping can avoid the interaction between pumps,nonlinear effects and FWM which are caused by WDM(wave division multiplexing)system.Compared with backward pumping,the signal is more easily affected by nonlinear effects and spontaneous emission noise under forward-pumping,therefore the backward-pumping is applied.This thesis simulates the dispersion of FRA by multiwave backward TDM-pumping.Based on the nonlinear partial differential coupled-equations of FRA,the model can be described which transforms the effects of pumping into a gain function that is determined by the variation of distance.The effects of FRA can be simulated by analyzing the distribution of signal along the fiber under TDM-pumping with fiber dispersion coefficient,duty cycle and number of pumps.Based on analyzing the influence of output signal with the third order parameter,the width of signal and combination of pumping,simulations show that the duty-cycle of pumping and the number of pumping have little influence on the dispersion of FRA,and the second order parameter determines the shape of signal with symmetrical distortion while the third is unsymmetrical.