A micro fiber optic vibration sensor fabricated by femtosecond laser for high temperature applications

A micro vibration sensor fabricated by femtosecond laser for high-temperature applications is demonstrated. The sensor is based on the configuration of an extrinsic Fabry-Perot interferometer (EFPI), which is formed by a hollow core fiber (HCF) sandwiched between two sections of single mode fiber (SMF). Part of the HCF is removed by a femtosecond laser and a cantilever beam is obtained. A section of the SMF acting as the mass block can oscillate vertically when the sensor is subject to vibration. Within the frequency range of 20-300 Hz, the experimental results show that the sensitivity of 129.6 nm/g@100 Hz is achieved in the acceleration range from 0 to 3.01 g. The temperature response of the EFPI cavity is 0.225 nm/℃. The sensor can operate stably at a high temperature of 950℃.