Abstract

The monitoring of acoustic waves is essential for a variety of applications, ranging from photoacoustic imaging to industrial non-destructive evaluation and monitoring. Optical acoustic sensors have many advantages over electrical counterparts such as passivity and immunity to electromagnetic interference, and can be quite compact with all-fiber structures. A common approach is to optically detect the acoustically induced mechanical movement of a cantilever or a reflective membrane. However, sensors based on moving mechanical parts have limitations, because they are influenced by the mechanical properties of the structures involved that behave as a coupled spring-mass system. Here a new type of optical acoustic sensing concept based on a spherical microcavity fiber Fizeau interferometer is described. The sensor is fabricated by inserting a section of single-mode fiber into a spherical microcavity to form a Fizeau interferometer. Thanks to the elasto-optic effect, the sound pressure modifies the refractive index of the microcavity; then a corresponding change in the interferometric spectrum can be observed. The sensor was successfully used to detect acoustic waves under the whole audible region, from 20 Hz to 20 kHz. The experimental results show that the sensitivity can be improved via altering the length of microcavity. The structure is membrane-free, and the sensitivity will not be limited by these size restrictions which makes the technology an interesting alternative to conventional transducers for acoustic wave measurement.

© 2019 Optical Society of America

Ultracompact optical fiber acoustic sensors based on a fiber-top spirally-suspended optomechanical microresonator

Mian Yao, Yangxi Zhang, Xia Ouyang, A. Ping Zhang, Hwa-Yaw Tam, and P. K. A. Wai
Opt. Lett. 45(13) 3516-3519 (2020)

Membrane-free acoustic sensing based on an optical fiber Mach–Zehnder interferometer

Wenhua Zhu, Danyang Li, Jiaojiao Liu, and Ruohui Wang
Appl. Opt. 59(6) 1775-1779 (2020)

Ultrasound sensing based on an in-fiber dual-cavity Fabry–Perot interferometer

Huibo Fan, Liang Zhang, Song Gao, Liang Chen, and Xiaoyi Bao
Opt. Lett. 44(15) 3606-3609 (2019)

On-chip silicon Mach–Zehnder interferometer sensor for ultrasound detection

Boling Ouyang, Yanlu Li, Marten Kruidhof, Roland Horsten, Koen W. A. van Dongen, and Jacob Caro
Opt. Lett. 44(8) 1928-1931 (2019)

All-fiber acoustic particle velocity sensor based on graphene-coated four-core fiber

Ran Gao and Xiangjun Xin
Opt. Lett. 44(18) 4439-4442 (2019)