Silicon-photonics focused ultrasound detector for minimally invasive optoacoustic imaging

• Published in: Biomedical optics express Vol. 13; no. 12; pp. 6229 - 6244
• Main Authors: Nagli, Michael, Koch, Jürgen, Hazan, Yoav, Volodarsky, Oleg, Ravi Kumar, Resmi, Levi, Ahiad, Hahamovich, Evgeny, Ternyak, Orna, Overmeyer, Ludger, Rosenthal, Amir
• Format: Journal Article
• Language: English
• Published: United States Optica Publishing Group 01.12.2022
• ISSN: 2156-7085; 2156-7085
• DOI: 10.1364/BOE.470295

One of the main challenges in miniaturizing optoacoustic technology is the low sensitivity of sub-millimeter piezoelectric ultrasound transducers, which is often insufficient for detecting weak optoacoustic signals. Optical detectors of ultrasound can achieve significantly higher sensitivities than their piezoelectric counterparts for a given sensing area but generally lack acoustic focusing, which is essential in many minimally invasive imaging configurations. In this work, we develop a focused sub-millimeter ultrasound detector composed of a silicon-photonics optical resonator and a micro-machined acoustic lens. The acoustic lens provides acoustic focusing, which, in addition to increasing the lateral resolution, also enhances the signal. The developed detector has a wide bandwidth of 84 MHz, a focal width smaller than 50 µm, and noise-equivalent pressure of 37 mPa/Hz - an order of magnitude improvement over conventional intravascular ultrasound. We show the feasibility of the approach and the detector's imaging capabilities by performing high-resolution optoacoustic microscopy of optical phantoms with complex geometries.