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Proceedings Paper

Interferometric and fibre Bragg grating sensor interrogation using an arrayed waveguide grating
Author(s): David C. C. Norman; David J. Webb; Ralf D. Pechstedt
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Paper Abstract

We investigate the use of an arrayed waveguide grating (AWG) to interrogate both fibre Bragg grating (FBG) and interferometric sensors. A broadband light source is used to illuminate both the FBG and interferometric sensors. Reflected spectral information is directed to an AWG with integral photodetectors providing 40 electrical outputs. To interrogate interferometric sensors we investigated the dual wavelength technique to measure the distance of a Fabry-Perot cavity, which produced a maximum unambiguous range of 1440μm with an active sensor. Three methods are described to interrogate FBG sensors. The first technique makes use of the reflected light intensity in an AWG channel passband from a narrow bandwidth grating, giving a usable range of 500με and a dynamic strain resolution of 96nε/√Hz at 30Hz. The second approach utilises wide gratings larger than the channel spacing of the AWG; by monitoring the intensity present in corresponding AWG channels an improved range of 1890με was achieved. The third method improves the dynamic range by utilising a heterodyne approach based on interferometric wavelength shift detection providing a dynamic strain resolution of 17nε/√Hz at 30Hz.

Paper Details

Date Published: 1 September 2004
PDF: 8 pages
Proc. SPIE 5459, Optical Sensing, (1 September 2004); doi: 10.1117/12.545069
Show Author Affiliations
David C. C. Norman, Aston Univ. (United Kingdom)
David J. Webb, Aston Univ. (United Kingdom)
Ralf D. Pechstedt, Bookham Technology Plc. (United Kingdom)

Published in SPIE Proceedings Vol. 5459:
Optical Sensing
Brian Culshaw; Anna Grazia Mignani; Rainer Riesenberg, Editor(s)

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