Truly Distributed Fiber Vibration Sensor Using Pulse Base BOTDA With Wide Dynamic Range

We report on what we believe to be the first truly distributed fiber vibration sensor based on pulse base Brillouin optical time-domain analysis (BOTDA). The pulse base approach is used to realize one-end one-laser simplification of the BOTDA system, in which the modulated pulse creates the probe wave and interacts with the pulse pump. Short pulse ( 10 ns) is used to enhance the dynamic range for the sensed object. A signal acquisition system with a 1-GHz sampling rate and 2-kHz trigger rate is employed to measure the truly distributed vibrations along the sensing fiber. With 6.25-ns pulsewidth, 160-MHz dynamic range is verified and different vibrations with 0-, 1.4-, and 2.4-Hz frequency components are distinguished in a 168-m sensing range. The experimental results demonstrate that this proposed sensor may be applicable for distributed dynamic measurements of large structural components.