title: Fiber-optic ultrasonic hydrophone using short Fabry-Perot cavity with multilayer reflectors deposited on small stub.
abstract: A fiber-optic probe with dielectric multilayer films deposited on a small stub is studied for mega-hertz ultrasonic-wave detection in water. The small stub with a short Fabry-Perot cavity and distributed reflectors is attached on the fiber end. The structure is mechanically strong and withstands intense ultrasonic pressure. Ultrasonic waves at 1.56MHz are successfully detected in water with a good signal-to-noise ratio. The working principle and the characteristics are studied by comparing the ultrasonic sensitivity with that of a conventional piezoelectric hydrophone. The distance response and directional response are also investigated.
authors.affiliation: Precision and Intelligence Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan. Electronic address: kskim@sonic.pi.titech.ac.jp.
authors.forename: Kyung-Su
authors.initials: KS
authors.lastname: Kim
authors.affiliation: Precision and Intelligence Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Mizuno
authors.affiliation: Precision and Intelligence Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nakamura
keywords: Band-pass filter; Dielectric multilayer film; Fabry–Perot resonator; Optical fiber sensor; Ultrasonic hydrophone