Influence of amplifier spontaneous emission noise on distributed acoustic monitoring systems

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.