A Study on Low-Frequency FBG Acceleration Transducer for Seismic Monitoring

In response to the fact that it is difficult for current optical transducers to meet requirements on low-frequency seismic vibration monitoring, a low-frequency fiber Bragg grating (FBG) acceleration transducer designed with double curved beam reed as pickup structure was proposed, and its structural parameters were analyzed and optimized and tested in a low-frequency vibration test system. The result suggested that the acceleration transducer functioned at a natural frequency of 41 Hz and offered flat response at 2–32 Hz; its lower frequency limit, dynamic range, and sensitivity were 0.5 Hz, 76.8 dB, and 966.65 pm/g, respectively; the acceleration transducer exhibited favorable linearity and resistance to lateral interference. Compared with other FBG sensors for measuring low-frequency vibration characteristics, the weight of the double-curved beam reed FBG sensor is 200 g and the volume is only 40 cm3, which can provide reference for promoting the engineering application of the FBG acceleration sensor in the field of low-frequency vibration measurement.