Analysis of threshold characteristics of fibre Raman amplifier

To study theoretically the threshold characteristics of fibre Raman amplifier(FRA),at first,the course of FRA's threshold through the coupling equations of stimulated Raman scattering was presented and the numerical simulation results were given.Then,based on the study before,the theoretical expression of forward-pumped and backward-pumped FRA's threshold were obtained considering the practical factors and the effect of all parameters on the threshold was studied in detail under the condition of five typical kinds of fibres.The results are:threshold are different with different pumping ways and in the same pumping way,each parameter has different effects on threshold.Finally,conclusion has been got that the threshold of the amplifier can be reduced based on different effects of each parameter,which gives some advices for improving the pump efficiency and experiment work of the amplifier.