A Single-Element Fiber Transducer for All-Optical Ultrasound and Photoacoustic Sensing

Abstract

The past few decades have seen a rapid rise in minimally invasive medical procedures performed around the globe. These procedures have been made possible largely because of innovations in medical imaging and sensing to guide physicians in performing the interventions safely. Ultrasound technology has remained highly popular through this transition due to its safety and efficacy. However, the demand for miniature flexible devices for increased accessibility has prompted a shift toward all-optical ultrasound devices. Additionally, photoacoustic imaging and sensing have emerged as a promising technology with abilities to enhance diagnostic capabilities in several clinical applications, most significantly in the imaging of atherosclerotic plaque. The Fabry-perot ultrasound detector, being one of the more widespread optical ultrasound detection technologies, has been explored significantly in this context. This thesis presents a novel wave-guided configuration for fiber Fabry-Perot ultrasound detectors. This work demonstrates 16 times higher sensitivity than traditional piezoelelectric technology at comparable size scales. The chapters that follow present the simulations and experiments conducted around (a) optimizing the fabrication of the wave-guided fiber Fabry-Perot devices, (b) the complete optical and acoustic characterization of the fabricated devices, and (c) the potential improvements that can be made with incorporating dielectric mirrors. The thesis concludes with a discussion on the possible configurations for creating a complete ultrasound and photoacoustic probe for guiding minimally invasive interventions.