Silicon photonic MEMS platform-based air-coupled optomechanical ultrasound receiver at 2.8 MHz with an ultra-compact active acoustic sensing area

Abstract

High-resolution non-contact non-destructive evaluation (NDE) utilizing MHz-range ultrasound in air-coupled environments faces two significant challenges: severe signal attenuation and reduced sensitivity due to transducer miniaturization. Optical ultrasound sensors have emerged as promising candidates to overcome these limitations; however, widespread adoption remains challenging. Conventional discrete optical sensors are limited by complex fabrication and rigid form factors. Furthermore, the efforts to implement these on photonic integrated circuits (PICs)-while addressing scalability-are typically constrained by limited sensitivity. To address these requirements, we report a chip-scale optomechanical ultrasound receiver implemented, for the first time, on a silicon photonics MEMS platform. This platform facilitates CMOS-compatible scalability and design freedom to independently optimize mechanical components and optical sensitivity. Consequently, the receiver demonstrates a compact active acoustic sensing area of 4 & times; 10-4 mm2. Despite this size reduction, in the noise-equivalent pressure (NEP)-active-area comparison, the proposed receiver's measured and estimated NEP values are positioned within a range comparable to or lower than those for previously reported air-coupled optical and CMUT sensors, when interpreted relative to the ideal area-scaling trend. Designed for a 2.8 MHz mechanical resonance, the receiver was benchmarked against a commercial 1 MHz air-coupled PZT transducer to provide a practical, controlled experimental baseline. In this controlled experimental comparison, the receiver showed a more than 25,000-fold higher received response per unit active acoustic area than the PZT baseline, serving as a complementary metric for unit-area received response and structural scaling potential. These findings suggest that the silicon photonic MEMS platform can provide a route toward compact, dense-array-compatible optical ultrasound receivers for localized air-coupled sensing. (c) 2026 Chinese Laser Press