Detection of acoustic pressure with hollow-core photonic bandgap fiber.

We report the results of our preliminary investigation on the use of hollow-core photonic bandgap fiber (HC-PBF) for hydrophone application. The response of the commercial HC-1550-02 fiber to acoustic pressure, in terms of normalized responsivity (NR), is measured to be - 334.4 dB re 1 microPa(-1). This agrees well with the theoretically predicated value of -331.6 dB re 1 microPa(-1) and is about 15 dB higher than that of the conventional fiber (HNSM-155). With straightforward fiber structure modifications (thinner outer silica cladding and higher air-filling ratio of inner microstructured cladding), the NR could be further enhanced to - 310 dB re 1 microPa(-1).