Abstract: Aiming at the problem of frequent earthquakes and other natural disasters, based on the research on distributed fiber-optic sensing technology and the sensing principle and basic theory of Michelson fiber-optic interferometer, we designed a vector seismic sensor. The sensitive part of the fiber-optic seismic sensor was mainly composed of elastic thin sheets, mass blocks, circular rings and sensing fiber-optic  components. We conducted strain effect analysis of the sensor and designed overall scheme of the system. The signal generator was used to simulate earthquakes with the signal amplitude of  1 and the frequencies of 300,500 Hz, respectively. The results show that the composite materials are ideal materials for the vibrating thin sheet, which can significantly improve the sensitivity of the system and reduce the system errors. The detection sensitivities are 0.08 g and 0.3 g, respectively. The amplitude of the seismic signal is basically consistent with the signal amplitude detected by the sensor, and it has a good frequency response, which can be used for detecting seismic waves.

Key words: distributed fiber-optic sensing, Michelson fiber-optic interferometer, seismic sensor, strain effect