The key operation of traditional Brillouin optical time-domain analysis (BOTDA) is the frequency-sweeping process to get the distributed Brillouin gain spectrum (BGS) whose central frequency (i.e. Brillouin frequency shift, BFS) has a linear relationship with the environmental information (e.g. temperature or strain) over the sensing fiber. However, this time-consuming process has limited the sampling rate of BOTDA. In this paper, we summarize several fast BOTDA systems for dynamic strain measurement which is developed by our team and refers to frequency-agile technique, slope-assisted methods and optical chirp chain technique.
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