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Proceedings Paper

Thickness-modulated waveguides for integrated optical sensing
Author(s): Kaspar Cottier; Rino E. Kunz; Guy Voirin; Max Wiki
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Paper Abstract

Novel sensor chips for evanescent wave sensing have been developed and investigated for various (bio-) chemical applications. A preferred integrated optical sensing scheme requires an array of independent sensing pads being present on the chip, each one of them having two different regions for in- and out coupling of the optical readout beam. We present a novel chip type, where this goal is achieved by thickness variations of the waveguiding film and one single grating period. The sensor chips consisted of a 300 nm thick Ta2O5 waveguide deposited on a glass substrate structured with a uniform grating of 360 nm period. By this optical structure a first coupling angle was defined. Sensing pads with a different coupling angle were realized by etching the film at selected regions down to a thickness of about 150 nm. The performance of the novel chips was demonstrated in various refractometric sensing applications. The experiments included cover medium refractive index variation as well as monitoring of affinity binding of small molecules. A very high resolution of 3x10-8 in the effective refractive index was achieved. The emphasis of this paper is on describing this approach and on presenting optical chip characterization methods together with modeling results.

Paper Details

Date Published: 26 March 2002
PDF: 11 pages
Proc. SPIE 4616, Optical Fibers and Sensors for Medical Applications II, (26 March 2002); doi: 10.1117/12.463824
Show Author Affiliations
Kaspar Cottier, Ctr. Suisse d'Electronique et de Microtechnique SA (Switzerland)
Rino E. Kunz, Ctr. Suisse d'Electronique et de Microtechnique SA (Switzerland)
Guy Voirin, Ctr. Suisse d'Electronique et de Microtechnique SA (Switzerland)
Max Wiki, Unaxis Balzers Ltd. (Liechtenstein)

Published in SPIE Proceedings Vol. 4616:
Optical Fibers and Sensors for Medical Applications II
Israel Gannot, Editor(s)

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