介绍了二阶DRA(分布式拉曼放大器)的结构原理和等效噪声指数, 在此基础上, 通过实验和理论分析研究了二阶DRA的噪声特性与一阶二阶泵浦注入比例的关系。结果表明, 放大器增益基本不变时, 二阶泵浦光注入比例越大, 等效噪声指数越小; 通过适当地调整一阶二阶泵浦功率, 可使放大器工作在更小噪声条件下, 使整个系统的噪声性能得以提升。

This paper introduces the structure of second-order Distributed Raman Amplifier (DRA) and the effective noise figure of DRA. Based on previous work, the relationship of the second order DRA’s noise characteristic and the injection ratio of first order and second order pump is investigated both in experiment and theory. It is found that when the amplifier gain is approximately constant, the greater the injection ratio of second order pump can be achieved with smaller effective noise figure. Therefore, through the appropriate adjustment of the first order and second order pump power, it can make the amplifier work on the smaller noise condition. The noise performance of the whole system can also be improved.