在小信号假设下推导出了双向泵浦分布光纤Ram an放大器 (Bi DFRA)中包括放大的自发辐射噪声和二次 Rayleigh散射噪声在内的等效噪声系数公式 ,并对光纤非线性进行了归一化。研究了不同偏振因子和 Rayleigh散射系数情况下等效噪声系数与 Raman总增益及其中正向增益比例的关系。结果与数值模拟很好符合 ,并给出了明确的物理解释。该文据此提出了 Bi DFRA设计的一些参考准则 Based on the small signal hypothesis, the equivalent noise figure formula including the amplified spontaneous emission noise and the quadratic Rayleigh scattering noise in bi-directional pump-distributed optical fiber amplifier (Bi DFRA) is deduced, and the fiber nonlinearity A change. The relationship between equivalent noise figure, total Raman gain and forward gain ratio under different polarization factors and Rayleigh scattering coefficients is studied. The results agree well with the numerical simulations and give a clear physical explanation. This paper proposes some reference guidelines for Bi DFRA design