Integrated photonic ultrasound transducers (IPUTs) are compact, high-sensitivity devices that combine mechanical sensing with optical readout using integrated photonics. IPUTs typically consist of optical waveguides integrated on a thin mechanical plate that serves as the acoustic sensing element. In many realizations, this plate is formed from thermally oxidized silicon dioxide layers commonly used in photonic fabrication processes. The oxidation process introduces significant residual compressive stress–typically between 200 MPa and 400 MPa–as the structure cools to room temperature. Such stresses can strongly influence the dynamic response of the plate through their contribution to the geometric stiffness of the structure. In this work, the influence of internal stress on the resonance frequency and receive transfer function (RTF) of IPUTs is investigated. Finite element models incorporating residual stress and geometric nonlinearity are developed and validated against experimental measurements and results reported in the literature. Parametric analysis shows that increasing compressive stress progressively reduces the resonance frequency while enhancing the RTF as the structure approaches the critical buckling condition. Beyond this point, changes in the prestressed equilibrium configuration lead to transitions in the dominant vibration mode, producing abrupt variations in the resonance frequency and RTF. These results highlight the importance of accounting for residual stress in the design and analysis of IPUTs and similar plate-based acoustic sensors to ensure reliable dynamic performance and predictable sensitivity.

A high signal-to-noise ratio (SNR) is critical for sensitive ultrasound applications. Unlike traditional piezoelectric sensors that rely on material properties, an integrated photonic ultrasound transducer (IPUT) separates sensing and read-out systems, allowing for better optimization. Here we use a silicon Mach–Zehnder interferometer (MZI) embedded in a circular silicon dioxide membrane, where incident acoustic pressure modulates the optical phase. We extend the semi-analytical model introduced in our previous work to incorporate the device geometry and fabrication-induced internal stress, enabling accurate prediction of the transducer’s optomechanical response. This approach resulted in an experimentally measured sensitivity of 0.47 pm/Pa at a resonance frequency near 1 MHz, in close agreement with the model prediction of 0.46 pm/Pa. This performance represents a sevenfold improvement over previously reported devices [Lienders et al., Sci. Rep., 2015]. Additionally, we have developed two more IPUTs where multiple membranes were cascaded and their performance was experimentally investigated. The IPUT with three membranes had an RTF of 1.4 pm/Pa, while the IPUT with five membranes’ RTF was 2.24 pm/Pa. Our IPUTs also have excellent noise performance, as demonstrated by the noise equivalent pressure (NEP) of the device. NEP of IPUT with one membrane is 42.5 mPa, IPUT with three membranes is 15.5 mPa, and the IPUT with five membranes is 14.2 mPa. Compared to the state-of-the-art ultrasound sensors, our IPUT with five membrane shows 35 times lower NEP. Our results demonstrate that fabrication-aware modeling is crucial for achieving optimal sensitivity in IPUTs, establishing the proposed IPUT as a promising solution for underwater ultrasound sensing.