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Proceedings Paper

Novel macrobend sensor structure based on selective launch of the fundamental mode in graded index multimode fiber
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Paper Abstract

Novel optical fiber sensor architecture has been developed. The actual element of the sensor is highly curved multimode fiber. However, the feed to the multimode fiber is through a single mode fiber to ensure that only the lowest order spatial mode is launched. Similarly the receiver is also coupled to the sensing element through a single mode fiber. The fundamental mode within graded index multimode fiber proves to be very insensitive to macrobends, if bend radius is larger than certain critical value. If bend radius is reduced below critical value the loss increases very rapidly and this allows for construction of relatively sensitive macrobend fiber optic sensor. In this paper we describe a quantitative theoretical model and a corresponding experimental investigation of the proposed structure. A proposal for simple and practical sensor design based on the proposed structure is presented. It is consisted of a miniature fiber optic coil that is deformed proportionally to the measured environmental parameter. We practically demonstrated sensitivities in the range of ΔI/Δx=130%/N and ΔI/ΔF= 1.1%/μm. Even higher sensitivities are possible by proper mechanical construction of the sensor element. The proposed structure can configured in variety of different distributed and quasi-distributed architectures and is suitable for embedding into the composite materials.

Paper Details

Date Published: 12 June 2000
PDF: 7 pages
Proc. SPIE 3986, Smart Structures and Materials 2000: Sensory Phenomena and Measurement Instrumentation for Smart Structures and Materials, (12 June 2000); doi: 10.1117/12.388122
Show Author Affiliations
Denis Donlagic, Univ. of Maribor (Slovenia)
Brian Culshaw, Univ. of Strathclyde (United Kingdom)

Published in SPIE Proceedings Vol. 3986:
Smart Structures and Materials 2000: Sensory Phenomena and Measurement Instrumentation for Smart Structures and Materials
Richard O. Claus; William B. Spillman Jr., Editor(s)

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