Study On Gain Flattening Of Fiber Raman Amplifier By TDM Pumping

A fiber Raman amplifier(FRA) plays an important role in high speed dense wavelength division multiplexing(DWDM) fiber communication because of rapid response, saturated big output power, and distributed amplifying, etc. People focuses on such as gain flattening which is based on multi-wavelength pumping sources pumping simultaneously(WDM pumping) that usually causes system degeneration because of nonlinearity.In order to solve the problem of system degeneration under WDM pumping, this thesis presents WDM – TDM(time division multiplexing) pumping for gain flattening of FRA. By choosing multiple wavelength sources for TDM pumping, it can avoid the interaction between pumping sources to generate four –wave mixing. Backward pumping is chosen because of smaller noises compared with forward pumping. On-off gain has been got, and simulation has been done with the combination of pumping powers and duty cycle for TDM-pumped FRA.Simulation results demonstrate that the gain flattening changed with the combination of pumping power and duty cycle. When optimized-pumping-power-combination or optimized-duty-cycle-combination is chosen, better gain and gain flattening have been got. When optimized-pumping-power-combination and optimized-duty-cycle-combination are chosen, on-off gain and gain ripple rise a little. This is because noise and pumping repetition rate have great influence on gain flattening.