针对光放大器中高增益和低噪声系数之间存在矛盾的问题，利用掺铒光纤作为放大介质，采用两级掺铒光纤放大结构，并在两级之间加入前后向放大自发辐射（ASE）噪声抑制单元的实验方案，搭建了高增益、低噪声系数的掺铒光纤放大器。利用插值法，更加准确测量ASE噪声功率，分析了掺铒光纤放大器(EDFA)的增益和噪声系数等性能参数，并与商用的低噪声光放大器进行对比测试。实验结果表明，搭建的掺铒光纤放大器峰值增益为40.1 dB，噪声系数最低为3.8 dB，比量子极限高出0.8 dB，而且在相同输入功率和相同增益条件下，自行搭建的低噪声光放大器的噪声系数比商用低噪声光放大器低0.3 dB。

Considering the trade-off between the high gain and low noise figure in optical amplifier, a two-stage amplifier which has the structure to suppress the forward and backward-travelling amplified spontaneous emission noise with high gain and low noise figure based on Erbium-doped fiber is set up. Interpolation is used to test the power of amplified spontaneous emission (ASE) noise accurately. The gain and noise figures and some other parameters of the amplifier are analyzed. Comparison between the erbium-doped fiber amplifer (EDFA) and the commercial low noise EDFA is carried out. The results show that the highest gain of the EDFA in the experiment is 40.1 dB and the noise figure is 3.8 dB which is 0.8 dB above quantum-limit. The results when testing the amplifier and commercial EDFA in the same input power and gain show that the noise figure of the amplifier is 0.3 dB lower than the commercial EDFA.