Simultaneous measurement of acoustic pressure and temperature using a Fabry-Perot interferometric fiber-optic cantilever sensor

A Fabry-Perot (F-P) interferometric fiber-optic cantilever sensor is presented for simultaneous measurement of acoustic pressure and temperature, which are demodulated by a single high-speed spectrometer. The acoustic pressure wave pushes the cantilever to produce periodic deflection, while the temperature deforms the sensor and causes the F-P cavity length to change slowly. The absolute length of the F-P cavity of the fiber-optic cantilever sensor is calculated rapidly by using a spectral demodulation method. The acoustic pressure and temperature are obtained by high-pass filtering and averaging the continuously measured absolute cavity length value, respectively. The experimental results show that the acoustic pressure can be detected with an ultra-high sensitivity of 198.3 nm/Pa at 1 kHz. In addition, an increase in temperature reduces the resonant frequency of the acoustic response and increases the static F-P cavity length. The temperature coefficient of the resonance frequency shift and the temperature response of the sensor are -0.49 Hz/degrees C and 83 nm/degrees C, respectively. Furthermore, through temperature compensation, the measurement error of acoustic pressure reaches +/- 3%. The proposed dual parameter measurement scheme greatly simplifies the system structure and reduces the system cost. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement