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Proceedings Paper

Refractive-index sensors based on coupling to high-index multimode overlays
Author(s): David G. Moodie; Walter Johnstone; Graham Thursby; Kevin J. McCallion
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Paper Abstract

The evanescent coupling between a side polished fiber and a high index multi-mode slab waveguide produces resonances in the wavelength response of the device. The position of these resonances is sensitive to the thickness/index of the superstrate layer. This structure could then provide either film growth monitors or refractive index sensors. The sensitivity of the device is dependent upon the parameters of the slab waveguide and we present here both theoretical and experimental results for a selection of slab indices and thicknesses. The device is capable of detecting index changes of < 4 X 10-5 and with the use of an active material, such as lithium niobate, in the role of the overlay it offers the potential for a closed loop sensor.

Paper Details

Date Published: 30 April 1993
PDF: 6 pages
Proc. SPIE 1796, Chemical, Biochemical, and Environmental Fiber Sensors IV, (30 April 1993); doi: 10.1117/12.143569
Show Author Affiliations
David G. Moodie, Univ. of Strathclyde (United Kingdom)
Walter Johnstone, Univ. of Strathclyde (United Kingdom)
Graham Thursby, Univ. of Strathclyde (United Kingdom)
Kevin J. McCallion, Univ. of Strathclyde (United Kingdom)

Published in SPIE Proceedings Vol. 1796:
Chemical, Biochemical, and Environmental Fiber Sensors IV
Robert A. Lieberman, Editor(s)

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