多路干涉对光纤拉曼放大器噪声因数的影响

考虑了多路干涉与拉曼自发辐射噪声具有不同的谱分布特性，推导出信号的背向瑞利散射导致的多路干涉对光纤拉曼放大器噪声因数影响的解析表达式，给出了考虑多路干涉后光纤拉曼放大器的噪声因数的光学测量方法。分析了不同开关增益、不同输入信号功率、不同增益光纤背向瑞利散射情况下多路干涉对光纤拉曼放大器噪声因数的劣化程度。随着拉曼增益的增加，输入信号功率越大、背向瑞利散射越大，多路干涉的影响越大。

Impact of Multipath Interference on Noise Figure of Fiber Raman Amplifiers

The impact of multipath interference (MPI) on the noise figure of fiber Raman amplifier is studied. The noise figure is analytically expressed in terms of the Raman gain and the Rayleigh scattering parameters of the Raman fiber. The difference between the power spectral characteristics of the multipath interference noise and that of the Raman spontaneous emission noise is considered. It is demonstrateed that the MPI can be a significant degrading factor to the noise figure when the Raman on-off gain and the input signal power are increased. A modified noise figure measuring method is proposed so that the noise figure accounts for the MPI deriving from the sum of Rayleigh backscattering signal components.