Seismic wave detection system based on fiber optic sensor

In this paper we will demonstrate our fiber Bragg grating (FBG) accelerometer system in seismic wave detection applications. Optical fiber sensors using fiber Bragg grating have a number of advantages such as immune to electromagnetic interference, lightweight, and low power consumption. Most important, the FBG sensor has high sensitivity to dynamic strain signals and the strain sensitivity can approach sub micro-strain. The basic principle of the FBG seismic sensing system is that it transforms the acceleration of ground motion into the strain signal of the FBG sensor through mechanical design, and after the optical demodulation generates the analog voltage output proportional to the strain changes. The customized FBG seismic sensor prototype is described, which includes the electro-optical design, mechanical design and the hardware and software interface of the sensor system. The laboratory evaluation of the system is performed systematically on a commercial vibration stage. Studies of the sensor properties show that the sensor has a high sensitivity (2500 mV/g at 90 Hz) to the acceleration signal, a large dynamic range (80 dB), the good linearity and stability after device integration and packaging.