Sapphire optical fiber high-temperature vibration sensor.

A sapphire fiber high-temperature vibration sensor with an extrinsic Fabry-Perot interferometer (EFPI) structure is proposed and experimentally demonstrated. The vibrating diaphragm of the sensor is a supported beam structure fabricated by etching a single-side polished sapphire wafer using a femtosecond laser. The FP cavity of the sensor is composed of the sapphire fiber end face and the polished surface of the vibrating diaphragm. The interference signal of the sensor is picked up by the sapphire fiber and transmitted to a laser interferometry demodulator through a multimode fiber. Experimental results show that the acceleration response is linear in the range of 0-10 g along with an acceleration sensitivity of 20.91 nm/g. The resonance frequency of the sensor is 2700 Hz, which is consistent with the ANSYS simulation results. The sensor can also work in the temperature range from room temperature to 1500 ℃, providing a feasible method for vibration measurements in high-temperature environments.