在同时考虑抽运光和信号光之间不同偏振态、多波长抽运以及抽运光和信号光损耗系数不同的情况下,导出了分布光纤拉曼放大器(DFRA)的等效噪声系数解析公式,并据此定量研究了抽运光和信号光之间的偏振关系对DFRA特性的影响以及DFRA与掺铒光纤放大器(EDFA)级联时系统光信噪比(OSNR)的改善ΔOSNR.指出:随着DFRA开关增益的增加,ΔOSNR会由线性增加逐渐变为对数增加而趋于饱和.解析结果与已发表文献的数值模拟结果基本吻合.

Analytical expressions of equivalent noise figure and other noise characteristics of distributed fiber Raman amplifier (DFRA) are derived under complex conditions. These conditions include difference in polarization state and attenuation coefficients between pump and signal light as well as multiple wavelength pumping. Accordingly, their impact on DFRA performance and optical signal to noise ratio improvement (ΔOSNR) of concatenated DFRA+EDFA is investigated. With increasing DFRA on off gain, ΔOSNR increases first linearly and then logarithmically, resulting in saturation. Results of this work agree well with numerical simulation of existing work.