Abstract

The use of a diamond rod to couple a blackbody source optically to a chalcogenide glass fiber is described and shown to be useful for evanescent-wave IR absorbance measurements. One end of a short 0.5-mm-diameter diamond rod abuts an optical fiber of the same diameter; the other end is in direct contact with a glowing silicon carbide IR source. The close match of the refractive indices of SiC, diamond, and AsSeTe fiber reduces optical losses at the interfaces, allowing a high overall throughput as well as transmission into the fiber of a wider range of transverse optical modes than is available with the use of through-air focusing methods. Use of the higher-order modes for evanescent-wave spectroscopy leads to increases in sensitivity, due both to increased evanescent pathlength and to a larger number of internal reflections per unit length.

Theory of fiber-optic, evanescent-wave spectroscopy and sensors

A. Messica, A. Greenstein, and A. Katzir
Appl. Opt. 35(13) 2274-2284 (1996)

Coupling efficiency evaluation of multimode fiber devices using GRIN rod lenses

Paola Accordi, Carlo P. Basola, Giam Paolo Bava, Guido Chiaretti, and Ivo Montrosset
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Evanescent-wave infrared spectroscopy of solid materials using deformable silver-halide optical fibers

I. Paiss, D. Bunimovich, and A. Katzir
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Transmission property and evanescent wave absorption of cladded multimode fiber tapers

Shangping Guo and Sacharia Albin
Opt. Express 11(3) 215-223 (2003)

Evanescent-wave infrared spectroscopy with flattened fibers as sensing elements

Y. Raichlin, L. Fel, and A. Katzir
Opt. Lett. 28(23) 2297-2299 (2003)