A new type of tunable broadband fiber-optic acousto-optic sensor was experimentally demonstrated by utilizing a bubble-on-fiber (BoF) interferometer. A single micro-bubble was generated by injecting a heating laser at λ = 980 nm on the metalized facet of an optical fiber. The BoF formed a spherical micro-cavity in water whose acoustic deformation was precisely detected by using a narrowband DFB laser at 1550 nm. The heating light and the interrogating light were fed into a single fiber probe by wavelength division multiplexing (WDM) realizing a small footprint all-fiber configuration. The diameter of the BoF was stabilized with a variation less than 0.5 nm by fast servo-control of the heating laser power. The stabilized BoF served as a Fabry-Pérot cavity that can be deformed by acoustic perturbation, and a minimum detectable pressure level of as low as ~1 mPa/Hz1/2 was achieved in a frequency range of over 60 kHz in water at room temperature. Our proposed BoF technology can provide a tunable, flexible and all-fiber solution to detect minute acoustically driven perturbations combining high-precision interferometry. Due to the very small form-factor, the technique can find applications of liquid-immersible in situ measurements in bio-molecular/cell detection and biochemical phenomena study.
Bibliographical noteFunding Information:
National Science Foundation of China (No. 61705082); Natural Science Foundation of Guangdong Province (No. 2017A030313361). We thank Prof. Wei Jin in the Department of Electrical Engineering, The Hong Kong Polytechnic University and Prof. Kai Chen in the Institute of Photonics Technology, Jinan University for their proof reading of the manuscript.
© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics