High Figure of Merit and Low Cross Sensitivity Fiber Bragg Grating Accelerometer Based on Double Grid-Diaphragms

Use of a detailed parallel theoretical model has allowed the design of a high figure of merit and low cross sensitivity accelerometer based on fiber Bragg grating (FBG), and the good response characteristics have been demonstrated experimentally. The relationship between the sensitivity and resonant frequency is downplayed, the mechanism of expanding the frequency band and maintaining higher sensitivity has been analyzed. A FBG accelerometer with a good performance of higher main-axis sensitivity and lower cross sensitivity has been presented. The experimental results obtained indicate that the FBG accelerometer has a broad frequency range from 1 to 60Hz, the corresponding sensitivity range from 754.3 to 763.2pm/G, while the fluctuation is less than 3dB. The resonant frequency is 103Hz, and the corresponding cross sensitivity is less than -24.76dB (<5%). The figure of merit is 78.61nm∙Hz/G, it shows that the sensor has better comprehensive characteristics. An accelerometer with this performance thus has the potential for application in low frequency oil and gas seismic exploration.