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arXiv · 2506.20219

Integrated optomechanical ultrasonic sensors with nano-Pascal-level sensitivity

Xuening Cao·Hao Yang·Min Wang·Zhi-Gang Hu·Zu-Lei Wu·Yuanlei Wang·Jian-Fei Liu·Xin Zhou·Jincheng Li·Chenghao Lao·Qi-Fan Yang·Bei-Bei Li
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Abstract

Ultrasonic sensors are widely used for object detection and localization in underwater and biological settings. The operational range and spatial resolution are inherently limited by sensor sensitivity, in which conventional piezoelectric transducers have been overwhelmed by advanced photonic sensors. Here, we demonstrate an optomechanical ultrasonic sensor integrated into a photonic platform, which comprises a suspended SiO2 membrane embedded with a high-Q Si3N4 microring resonator. By exploiting simultaneous optical and mechanical resonances, the sensor achieves a record low noise-equivalent pressure (NEP) of 218 nPa/Hz^1/2 at 289 kHz in air and 9.6 nPa/Hz^1/2 at 52 kHz in water. We demonstrate its versatility through photoacoustic gas spectroscopy in air and underwater ultrasound imaging, achieving a minimum detectable C2H2 concentration of 2.9 ppm (integration time 1 s) and an imaging resolution of 1.89 mm, respectively. Our work represents a significant advancement in compact CMOS-compatible ultrasound sensing, unlocking new possibilities in biomedical imaging, environmental monitoring, industrial testing, and underwater communications.

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Xuening Cao, Hao Yang, Min Wang, Zhi-Gang Hu, Zu-Lei Wu, Yuanlei Wang, Jian-Fei Liu, Xin Zhou, Jincheng Li, Chenghao Lao, Qi-Fan Yang, Bei-Bei Li. 2025-06-25. Integrated optomechanical ultrasonic sensors with nano-Pascal-level sensitivity. https://arxiv.org/abs/2506.20219

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