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Proceedings Paper

In-line fiber demodulators for interrogation of Bragg grating sensors
Author(s): Mark E. Jones; Jonathan A. Greene; Vikram Bhatia; Kent A. Murphy; Richard O. Claus; Anne E. Miller; Ashish M. Vengsarkar
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Paper Abstract

Optical fiber Bragg gratings, first demonstrated by Hill in 1978, will see increasing deployment as sensors in smart structure applications due to their minimal insertion loss and small profile. Bragg grating sensors provide narrowband reflections from a periodic index discontinuity. Strain and temperature changes occurring on the grating induce a shift in the reflected wavelength. Currently, the most basic Bragg grating demodulation system consists of monitoring the reflected wavelength with an optical spectrum analyzer, but use of these devices is limited due to high costs and poor frequency response. In this paper, we propose using dual-mode optical fiber as an intensity based interrogation system. The modal birefringence of the fiber is wavelength dependent and therefore, the phase relationship between two modes changes as a function of the Bragg grating reflected signal. We describe the optical architecture for this demodulation system and provide experimental data for temperature and vibration response. It is predicted that with an optical source operating at 300 microwatts, less than 1 microstrain resolution is achievable.

Paper Details

Date Published: 20 April 1995
PDF: 9 pages
Proc. SPIE 2444, Smart Structures and Materials 1995: Smart Sensing, Processing, and Instrumentation, (20 April 1995); doi: 10.1117/12.207680
Show Author Affiliations
Mark E. Jones, Fiber and Sensor Technologies, Inc. (United States)
Jonathan A. Greene, Fiber and Sensor Technologies, Inc. (United States)
Vikram Bhatia, Virginia Polytechnic Institute and State Univ. (United States)
Kent A. Murphy, Virginia Polytechnic Institute and State Univ. (United States)
Richard O. Claus, Virginia Polytechnic Institute and State Univ. (United States)
Anne E. Miller, AT&T Bell Labs. (United States)
Ashish M. Vengsarkar, AT&T Bell Labs. (United States)


Published in SPIE Proceedings Vol. 2444:
Smart Structures and Materials 1995: Smart Sensing, Processing, and Instrumentation
William B. Spillman, Editor(s)

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