Fast extraction for Brillouin frequency shift in BOTDA system

In this paper, we introduce the basic principle of the Brillouin optical time domain analysis (BOTDA) system and simulate the gain-type BOTDA system. In order to extract the Brillouin frequency shift more accurately, the filtering method is vitally important. In this letter, Gaussian filtering, median filtering and hybrid filtering are used to remove the noise respectively. It is observed that hybrid filtering has the best performance among the three methods, which can improve the signal-to-noise ratio by 9.18 dB. Besides, a peak location method is proposed to quickly extract the center frequency of the filtered Brillouin gain spectrum. This method reduces processing complexity by omitting Lorentz fitting and it possesses the advantages of fast processing rate and high accuracy. Therefore, the peak location method we proposed can be considered as an attractive method for extracting temperature distributions.