Abstract

A tunable broadband fiber-optic acoustic sensor was demonstrated by utilizing a bubble-on-fiber (BoF) interferometer. Single micro-bubble was photothermally generated by injecting a heating laser at λ= 980 nm on the metalized facet of an optical fiber. With a servo-control process, the BoFs were stabilized with a diameter variation of less than 0.5 nm. This stable/quasi-static BoF served as a Fabry-Pérot cavity that can detect acoustic perturbation with a noise equivalent pressure level of ~ 1 mPa/Hz^1/2 over a frequency range widely tunable from kHz to MHz. The sensitive and broadband BoFs were applied to underwater acoustic sensing and photoacoustic imaging.

© 2018 The Author(s)