We present sensitive ultrasound sensors with an innovative silicon photonic optomechanical waveguide that features a 15-nm gap between movable parts [Nature Photonics 15, 341 (2021)]. Sensors are fabricated using CMOS-compatible processing and tested for biomedical imaging. @en

Photoacoustic tomography defines new challenges for ultrasound detection compared to ultrasonography. To address these challenges, a sensitive, small, scalable, and broadband optomechanical ultrasound sensor (OMUS) has been developed. The OMUS is an on-chip optical ultrasound sensor, using optical interferometric ultrasound detection. It consists of an acoustic membrane on top of an optical ring resonator that modulates the optical ring resonance with high efficiency enabled by an innovative optomechanical waveguide. Raster scanning photoacoustic tomography has been demonstrated with a single-element OMUS. Based on performance and form factor, the OMUS combined with passive optical multiplexing may enable new applications in photoacoustic imaging.

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Future applications of ultrasound and photoacoustic imaging require a matrix of small and sensitive ultrasound sensors with read-out through a flexible cable. Silicon photonic ultrasound sensors have good prospects: small and sensitive sensors, wafer-scale fabrication, and matrix read-out via single optical fiber using photonic multiplexing. Here, we discuss different types of silicon photonic ultrasound sensors and their applications. This includes our optomechanical ultrasound sensor with extreme sensitivity that is achieved with an innovative optomechanical silicon photonic waveguide in an acoustical membrane. We discuss limitations of state-of-the-art piezoelectric sensors, how silicon photonic sensors overcome these, and applications in medical imaging.@en

We propose a new opto-mechanical ultrasound sensor (OMUS) enabled by an innovative silicon photonics waveguide. We present experimental results up to 30 MHz, a 10-sensor array proof-of-concept and our latest findings.@en

Future applications of photo-acoustic imaging require a matrix of small (wavelength/2) and sensitive ultrasound sensors with read-out through a flexible cable. Integrated optical sensors have good prospects: small and sensitive sensors, wafer-scale fabrication, and matrix read-out via single optical fiber using on-chip optical multiplexing. We propose a new type of opto-mechanical ultrasound sensor (OMUS) in silicon photonic chip technology. By using an acoustically resonant membrane in combination with an innovative split rib-type photonic waveguide, we achieve extremely high sensitivity. We present our experimental results in the frequency range up to 30 MHz.@en