微槽式光学谐振腔超声传感效应验证*

摘 要：光学微腔的高灵敏度主要源于其结构在时间和空间上对光场的局域增强作用和频率选择作用。其结构在垂直于波导方向上形成了高反射的边界，形成了一种回声腔，使得光在波导内来回反射，从而增强了波导内部的光场强度。当外界存在微小的压力波动时，它将引起波导内部的介电常数和压力场的变化，从而改变了谐振腔内的模式场分布和传输特性，据此可以实现对微小的压力波动进行高灵敏度检测。本文设计了一种高品质因子（Q）的光波导微槽式环形谐振腔超声传感器，完成器件制备并搭建了测试系统，依据倏逝波效应实现了超声探测。测试结果表明，该传感器的品质因子为1.38×107，在800 kHz ~1 MHz范围内响应平坦，在900 kHz的信噪比可以达到27 dB，灵敏度达到 -168 dB。本文设计的传感器可以为水声探测等领域的研究提供关键技术支持。

Verification of ultrasonic sensing effect in microgroove optical resonant cavity

Abstract: The high sensitivity of optical microcavities is mainly due to its structure''s localized enhancement and frequency selection effects on the optical field in both time and space. Its structure forms a highly reflective boundary perpendicular to the waveguide direction, forming an echo cavity that allows light to reflect back and forth within the waveguide, thereby enhancing the intensity of the light field inside the waveguide. When there are small pressure fluctuations outside, it will cause changes in the dielectric constant and pressure field inside the waveguide, thereby changing the mode field distribution and transmission characteristics in the resonant cavity. Based on this, high sensitivity detection of small pressure fluctuations can be achieved.In this paper, a high quality factor (Q) optical waveguide microgroove resonant cavity ultrasonic sensor is designed, and the device preparation and testing system are completed.The ultrasound detection was achieved based on the evanescent wave effect. The experimental results demonstrate that the sensor has a quality factor of 1.38×107, with a flat frequency response from 800 kHz to 1 MHz, a signal-to-noise ratio of 27 dB at 900 kHz, and a sensitivity of -168 dB. The designed sensor provides key technical support for research in underwater acoustic detection and other related fields.