A vector accelerometer based on optical fiber cantilever with hybrid gratings

We proposed a high sensitivity vector accelerometer. The sensor is a cantilever structure composed of long-period fiber grating (LPFG) and fiber Bragg grating (FBG) in cascade. Its unique structure makes the wavelength drift of the LPFG caused by micro-vibration converted into the reflected light intensity of the FBG, and it is not affected by temperature changes. It has extended single-frequency response spanning from 10 to 5000 Hz, as well as flexible detection of vibration signals. The experimental results show that the output signal of the sensor changes linearly with the vibration acceleration in a certain range of 0.6-10.5 g, its working sensitivity is 1.57 mV/g and the lower limit of measurement can reach 0.03 mg. The direction of acceleration is identified by inducing an asymmetric LPFG structure, the directional test more than 10 dB. Benefiting from small size and high sensitivity, the sensor may have the potential to realize acceleration detection in a harsh environment.