Ultrafast ultrasound imaging by optical polymer microring resonator array and a dual optical frequency comb: a theoretical concept

Ultrasound imaging is typically based on the use of arrays of piezoelectric transducers that can both emit and receive ultrasound. It has recently been shown that on-chip optical microresonator transducers can achieve massive improvements in minimizing footprint and increasing both ultrasound sensitivity and bandwidth; however, the construction of practical arrays remains an open problem. We study the feasibility of making an array of optical microresonators for ultrafast imaging. As a proof of concept, we propose the design of a linear array of polymer microring resonators with equally spaced resonance frequencies. Optical dual-comb setup simultaneously interrogates the whole array's ultrasound perturbation by assigning each microring to a single comb tooth. Using an optical frequency comb for detection provides an efficient way of sampling a large array of transducers while using only a single balanced heterodyne detection scheme per branch.