title: Ultrasonic sensor employing two cascaded phase-shifted fiber Bragg gratings suitable for multiplexing.
abstract: An ultrasonic sensor based on two cascaded phase-shifted fiber Bragg gratings (PS-FBGs) is proposed and demonstrated. In place of an external cavity laser, a broadband amplified spontaneous emission light source is used to demonstrate multiplexing ability suitable for sensor networks. The system has a high sensitivity to ultrasonic waves generated by a PZT actuator placed 7.5 cm away from the PS-FBG, because of the steep slope in the center of the PS-FBG spectrum. A second advantage of the phase shift is to reduce the effective sensor length, leading to the achievement of broadband characteristics. A pencil lead break test was performed and all results are compared to a traditional PZT sensor.
authors: Institute of Industrial Science, the University of Tokyo, Meguro-ku, Tokyo, Japan. wuqi@iis.u‑tokyo.ac.jp
authors: Qi
authors: Q
authors: Wu
authors: Yoji
authors: Y
authors: Okabe