Miniaturized ultrasound detector arrays in silicon photonics using pulse transmission amplitude monitoring

Silicon photonics holds promise for a new generation of ultrasound-detection technology, based on optical res-onators, with unparalleled miniaturization levels, sensi-tivities, and bandwidths, creating new possibilities for minimally invasive medical devices. While existing fabri-cation technologies are capable of producing dense res-onator arrays whose resonance frequency is pressure sen-sitive, simultaneously monitoring the ultrasound-induced frequency modulation of numerous resonators has remained a challenge. Conventional techniques, which are based on tuning a continuous wave laser to the resonator wavelength, are not scalable due to the wavelength disparity between the resonators, requiring a separate laser for each resonator. In this work, we show that the Q-factor and transmission peak of silicon-based resonators can also be pressure sensi-tive, exploit this phenomenon to develop a readout scheme based on monitoring the amplitude, rather than frequency, at the output of the resonators using a single-pulse source, and demonstrate its compatibility with optoacoustic tomog-raphy.(c) 2022 Optica Publishing Group