Influence of probe pulse characteristics on SNR of Brillouin optical time domain reflectometer

Brillouin optical time domain reflectometer (BOTDR) has attracted extensive attention due to its advantages of one-end access and long-distance measurement. The measurement accuracy and sensing range of BOTDR are affected by the system signal-to-noise ratio (SNR), which is closely related to the characteristics of the probe light pulse. In this paper, the influence of two characteristics of probe light on SNR is theoretically analyzed and experimentally verified, including the extinction ratio (ER) and peak power. Firstly, the theoretical model of probe pulse extinction ratio (ER) and SNR in the BOTDR is established, and the SNR distribution versus different ER is analyzed. Both numerical simulation and experimental verification show that the SNR was enhanced with the increase of ER. Besides, the SNRs under different pulse peak power are also evaluated. The experimental results show that the SNR increases along with the peak power at the beginning but decreases when the peak power exceed a certain value. The research results provide a reference for selecting the appropriate probe pulse features in BOTDR for higher SNR.