针对光纤密集波分复用系统的增益平坦和带宽问题，提出用多波长泵浦组合的方式增加带宽，通过级联光纤使得拉曼光纤放大器的增益平坦。利用不同波长的多泵浦同时抽运同种光纤，增加信号光的传输带宽，采用线性拟合拉曼增益谱的方式使得拉曼光纤放大器的光信号实现前放大后补偿，在输出端获得较大的光输出信号功率，得到了良好的增益平坦度，并且传输带宽比单泵浦抽运时增大一倍。仿真结果表明：平均放大信号光功率为6.2 mW，平均增益为24.48 dB，增益平坦度为0.08 dB，传输带宽为25.6 nm。为增益平坦型宽带光纤拉曼放大器提供了一种新的实现方法。

In order to achieve gain flatness and increase the bandwidth in optical fiber dense wavelength division multiplexing system, we proposed a method to increase the bandwidth by multi-wavelength pump combination, and flat the gain of the Raman Fiber Amplifier (RFA) by cascaded optical fiber. We use different wavelengths of dual pump to pump the same kind of fiber and increase the transmission bandwidth. Linear fitting Raman gain spectrum is applied to achieve pre-amplification and compensation in RFA. Therefore, large light output signal power and good gain flatness are obtained. The transmission bandwidth is doubled compared to the bandwidth of single pump pumping case. The simulation results show that the proposed method can achieve average optical power of 6.2 mW, average gain of 24.48 dB, gain flatness of 0.08 dB, and transmission bandwidth of 25.6 nm. This paper presents a new method to realize gain-flattened broadband RFA.