High sensitivity fiber acoustic sensor tip working at 1550Â nm fabricated by two-photon polymerization technique

An ultracompact fiber acoustic sensor tip was fabricated by using two-photon polymerization technique. The fiber sensor tip was consisted of two sidewalls on the end surface of the single mode fiber and a film held up by the sidewalls, which forms fiber inline Fabry-Pérot micro-cavity. Owing to the fabrication advantages of two-photon polymerization technique, the quadrature phase bias point can be controlled at fix wavelength of 1550 nm by matching the cavity length with the film thickness accurately. At laser wavelength of 1550 nm, the acoustic pressure of the fiber sensor tip reaches 0.0508 ± 0.0052 nm/Pa. The fiber acoustic sensor tip can be suitable for both industrial and biomedical applications due to its high sensitivity, excellent biocompatibility, ultracompact size and independent of laser wavelength tuning.