Research on all-silica fiber-optic fabry-perot high-temperature vibration sensor

An all-silica fiber-optic Fabry-Perot (F-P) high-temperature vibration sensor is proposed to address sensor failure and signal distortion in extreme environments. A collimated coupling structure based on a silica ball lens enables integrated, non-contact signal transmission between the fiber and the sensitive structure. The sensitive units are batch-fabricated using MEMS and thermal pressure bonding technologies. By combining three-wavelength dynamic demodulation with spectral cross-correlation, the extraction of vibration signal and temperature compensation are realized, eliminating the interference of temperature fluctuations on vibration sensitily. Experimental results indicate that as the temperature increases from room temperature (23 °C) to 800 °C, the sensitivity of the sensor decreases from 1.051 nm/g to 0.8915 nm/g. After temperature compensation, the maximum residual sum of squares (RSS) of the sensor is 0.168, and the full-scale nonlinearity error does not exceed 1.033%. In dynamic response tests, the characteristic frequency of the sensor is considerably higher than 6000 Hz. The sensor exhibits high flatness within the frequency response range of 100−2000 Hz, and its sensitivity gradually increases between 2000 Hz and 6000 Hz, with a maximum increment of only 0.177 nm/g. Featuring high consistency, adhesive-free integration, and electromagnetic immunity, this sensor provides a robust solution for vibration measurement in high-temperature environments.