An Optical Acoustic Sensor Based on Grooved High- Q Ring Resonator Applied to Subatmospheric Pressure Environment

Optical waveguide ring resonators (OWRRs) with high quality factor can greatly enhance the interaction between light and matter, which shows great advantages in optical sensing and has become a research hotspot in recent years. In this article, the change of acoustic signal is perceived by the evanescent field, which is induced by grooving in the ring waveguide region of SiO2 OWRR. The acoustic characteristics of the optical acoustic sensor based on SiO2 grooved OWRR under different atmospheric pressures are studied in detail. In the atmospheric pressure range of 41–101 kPa, the optical acoustic sensor always maintains a broadband acoustic response of 400 Hz–59 kHz, and the response flatness is less than ±2 dB. The sound pressure sensitivity increases with the decrease of atmospheric pressure. At 41 kPa, the sound pressure sensitivity is as high as 1040.44 mV/Pa, which is 1.35 times higher than that at 101 kPa. At the same time, the optical acoustic sensor can detect an acoustic signal as low as 5.03 dB at a subatmospheric pressure of 41 kPa. In addition, the fluctuation error of sound pressure sensitivity of the sensor is less than 3% when tested in different temperature and humidity environments. The excellent acoustic detection performance of the optical acoustic sensor in the subatmospheric pressure environment indicates that it is very suitable for acoustic monitoring and acoustic diagnosis under subatmospheric conditions such as high-altitude areas and aerospace fields.