High-sensitivity ultrasonic phase-shifted fiber Bragg grating balanced sensing system

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...

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Bibliographic Details
Published inOptics express Vol. 20; no. 27; pp. 28353 - 28362
Main Authors Wu, Qi, Okabe, Yoji
Format Journal Article
LanguageEnglish
Published United States 17.12.2012
Subjects
Equipment Design
Equipment Failure Analysis
Photoacoustic Techniques - instrumentation
Refractometry - instrumentation
Transducers
Ultrasonics - instrumentation
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Summary: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.
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ISSN:1094-4087
1094-4087
DOI:10.1364/oe.20.028353