© 2022 Optica Publishing GroupÂ
Yoav Hazan, Michael Nagli, Ahiad Levi, and Amir Rosenthal
Abstract
Silicon photonics holds promise for a new generation of ultrasound-detection technology, based on optical resonators, with unparalleled miniaturization levels, sensitivities, and bandwidths, creating new possibilities for minimally invasive medical devices. While existing fabrication technologies are capable of producing dense resonator arrays whose resonance frequency is pressure sensitive, 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 sensitive, 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 tomography.
Fig. PTAM pressure measurements. (a) Transmission spectrum of π-BG at different static pressures. The legend notes the pressure in kPa. (b) Normalized power transmission, (c) peak transmission, (d) resonance width, and (e) resonance wavelength of π-BG at different pressure calculated from the spectrum plotted in panel (a). (f) Schematic configuration of simultaneous ultrasound signal detection. Ultrasound signal, generated by a transducer, impinges the detection array at an angle. The setup results in a slight delay difference of the ultrasound signal along the detector array. (g) and (h) Measured ultrasound signals of the setup in panel (f), for resonators presented in Figs. 1(e) and 1(f), respectively.
Yoav Hazan, Michael Nagli, Ahiad Levi, and Amir Rosenthal