Bubble-on-fiber (BoF): A built-in tunable broadband acousto-optic sensor for liquid-immersible in situ measurements

Hongsong Xu, Guanyu Wang, Jun Ma, Long Jin, Kyunghwan Oh, Bai Ou Guan

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)11976-11983
Number of pages8
JournalOptics Express
Issue number9
Publication statusPublished - 2018 Apr 30

Bibliographical note

Publisher Copyright:
© 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


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