放大器自发辐射噪声对分布式声波监测系统的影响

Influence of amplifier spontaneous emission noise on distributed acoustic monitoring systems

掺铒光纤放大器（Erbium Doped Fiber Amplifier，EDFA）是分布式声波监测系统的重要组成部分，对于提高信号光的传输距离和系统解调信号的信噪比至关重要。但EDFA的引入也不可避免地带来了放大器自发辐射（Amplifier Spontaneous Emission，ASE）噪声。利用一个分布式声波监测系统，分别研究了不同位置的EDFA产生的ASE噪声对系统解调信号的影响。结果表明，功率EDFA产生的ASE噪声对于系统解调信号的信噪比基本没有影响。而前置EDFA产生的ASE噪声会对系统解调信号的信噪比产生很大的影响，在系统中加入一个中心波长为1550．12nm，带宽为0．2nm的滤波器后，系统解调信号的信噪比从大约20dB增加到60dB。

Erbium Doped Fiber Amplifier （EDFA） is an indispensable part of the distributed acoustic monitoring system. It plays an important role in improving the transmission distance and the signal-to- noise ratio of the demodulation signal. However, the presence of the EDFAs will bring Amplifier Spontaneous Emission （ASE） noise generated by different EDFAs on the whole system. Using a filter with a bandwidth of 0.2 nm, the influence of ASE noise on the demodulation signal was observed. The ASE noise generated by the power-EDFA has no effect on the SNR of the demodulation signal. However, the ASE noise generated by the pre-EDFA will greatly affect the SNR of the demodulation signal. After adding a filter after the pre-EDFA with center wavelength of 1 550.12 nm and bandwidth of 0.2 nm, the signal-to-noise ratio of the demodulation signal was increased from about 20 dB to 60 dB.