Open AccessHigh-sensitivity ultrasonic phase-shifted fiber Bragg grating balanced sensing system
Author(s) -
Qi Wu,
Yoji Okabe
Publication year - 2012
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.20.028353
Subject(s) - fiber bragg grating , optics , materials science , sensitivity (control systems) , ultrasonic sensor , phase noise , signal (programming language) , laser , noise (video) , detector , optical fiber , phase (matter) , fiber optic sensor , fiber laser , acoustics , physics , electronic engineering , computer science , quantum mechanics , artificial intelligence , image (mathematics) , programming language , engineering
A high-sensitivity ultrasonic sensing system is proposed and demonstrated. In this system, a phase-shifted fiber Bragg grating (PS-FBG) is used as a sensor to achieve broadband and highly sensitive detection. The PS-FBG modulates the output of a tunable laser to detect the ultrasonic strain directly. Balanced photo-detector (BPD) is used for eliminating the DC component and further amplifying the AC component in the detected signal. Another major function of the BPD is to reject laser intensity noise. As a result, the minimum detectable strain is limited by the BPD's noise and laser frequency noise. The sensitivity of the system is 9 nε/Hz(1/2). Because of its high sensitivity, this system has the potential to be used in acousto-ultrasonic testing without amplifying the input signal and in practical acoustic emission detection.