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In this work a micro-seismic fiber Bragg grating (FBG) sensor system based on a narrow linewidth distributed feedback (DFB) laser is investigated. By automatic control of the temperature of the DFB laser, the wavelength of the laser can be locked in the −3 dB reflectivity spectrum of the FBG. So the FBG sensor system can be made immune to temperature. Using the reference channel, the measurement precision of the system is improved by wiping out the power noise of the DFB laser. Experiments on the sensor system's frequency character and linearity have been performed. Results show that this sensor has the smallest acceleration of 1 mm s −2 .

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