Developing whispering-gallery optical microprobes for ultrasound sensing (Conference Presentation)

The miniature probe-type ultrasound sensor with high sensitivity and bandwidth is important for the field of ultrasonic detection. Compared with piezoelectric material, pure optical ultrasound sensing has advantages in both sensitivity and bandwidth. Among those pure optical methods, the whispering gallery mode (WGM) resonators present superior characteristics including small size, wide bandwidth and high sensitivity. In this study, we report our recent work on developing miniature US sensor based on different types of WGM resonators. Unlike previously reported works, our strategy is to make miniature probe US sensor, which not only has a small effective sensing size less than 100 um, but also do not need a large supporting structure. Our microprobes have bandwidth over 100 MHz. Therefore, our microprobes have great potentials for sensing US within a very limited space (such as endoscopy) or very close to the target. The latter can effectively reduce the attenuation of high-frequency US in medium. We demonstrated our probes in both phantom and animal studies.