A Wide Frequency Response Fabry–Pérot Acoustic Sensor Based on the Self-Stabilization System

A self-stabilization system based on the operating point is built for measuring the membrane-free optical acoustic sensor constructed of a rigid Fabry–Pérot (F–P) cavity. The system can directly lock and track the quadrature point of the sensor's spectrum to realize broadband acoustic detection with high sensitivity. Compared with the demodulation system based on phase modulation spectrum technology, the system is simple in construction and has the advantage of fast real-time demodulation rate and wide detection bandwidth. The experimental results show the acoustic sensor achieves a wide frequency response of 700 Hz–411 kHz with a flatness of ±1.78 dB and a sensitivity of 31.83 mV/Pa, while the maximum detectable sound pressure reaches 136.9 dB. The sensor performs well in broadening the frequency response range, which includes a medium and high frequency range from 700 Hz to 20 kHz for noise monitoring, as well as an ultrasound range from 20 to 411 kHz for aeroacoustics and photoacoustic imaging. The improvement of the frequency band characteristics of the sensor in this research will further contribute to the development of application fields.