Integrated photonic ultrasound transducers; modelling and experimental validation (Conference Presentation)

A high signal-to-noise ratio is necessary for noise-sensitive ultrasound applications, a bottleneck for conventional ultrasound transducers (UTs) whose noise floor is limited by thermal electronic noise, which dominates their thermal acoustic noise. Integrated photonic ultrasound transducers (IPUTs) consisting of an optical circuit on a mechanical resonator can sidestep this limitation of conventional UTs. We present a semi-analytical model describing the dynamic response of the IPUT, which is used to design an extremely sensitive IPUT. After fabricating via the SOI platform, we performed underwater acoustic experiments to validate the IPUT. Our IPUT shows 25 times lower noise equivalent pressure (0.02 Pa) compared to the state-of-the-art UTs, which matches the model predictions within 10%. Thus, the IPUT outperforms conventional UTs for sensitive ultrasound applications, and the proposed model can accurately describe its behavior.