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Proceedings Paper

Free space optical coupling to completely embedded fiber Bragg grating sensors
Author(s): Liang Qiu; Keith W. Goossen; Dirk Heider; Daniel J. O'Brien; Eric D. Wetzel
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Paper Abstract

A novel method of free space passive optical coupling to completely embedded fiber Bragg grating (FBG) sensors has been investigated. Fiber optical sensors have attracted intense research and commercial interest. Specifically, fiber Bragg grating (FBG) sensors have shown great utility for integrity management and environmental sensing of composite structures. One major drawback of FBG sensors, however, is that they suffer from cumbersome and fragile techniques for bringing the sensing light into and out of the structures. In our previous publication, we have demonstrated surface normal free space coupling into embedded FBG sensors with 45-degree-angled mirrors integrated into fibers as the coupling technique. These previous studies, however, required physical coupling to detect and analyze the light transmitted through the FBG. In this paper, we successfully couple free space light into and out of an un-embedded FBG sensor using multimode fiber (MMF) spliced to SMFBG with 45-degree-angled mirrors fabricated onto both MMF and SMFBG on a polishing wheel. We also present a manual polishing technique to integrate mirrors onto MMF and SMF (without Bragg grating) embedded in a composite material, and successfully measure the coupling into and through these embedded optical fibers. With this approach, no pigtailing is needed, and the FBG sensors can be completely embedded inside the structures, greatly increasing system simplicity and robustness.

Paper Details

Date Published: 25 August 2010
PDF: 7 pages
Proc. SPIE 7787, Novel Optical Systems Design and Optimization XIII, 77870Y (25 August 2010); doi: 10.1117/12.861128
Show Author Affiliations
Liang Qiu, Univ. of Delaware (United States)
Keith W. Goossen, Univ. of Delaware (United States)
Dirk Heider, Univ. of Delaware (United States)
Daniel J. O'Brien, Army Research Lab. (United States)
Eric D. Wetzel, Army Research Lab. (United States)


Published in SPIE Proceedings Vol. 7787:
Novel Optical Systems Design and Optimization XIII
G. Groot Gregory; R. John Koshel, Editor(s)

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