Chemical sensing using infrared flattened fiber evanescent wave spectroscopy

Oded Spector*, Alla German, Lev Nagly, Abraham Katzir

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


The present paper describes a technique for enhancing the signal of fiber-optic evanescent wave spectroscopy (FEWS) in the infrared region, by flattening the sensing part of the fiber. FEWS is a novel method for measuring the absorption spectra of chemicals in contact with a segment of an optical fiber. It enables remote in-situ measurements using an optically closed system. The feasibility of FEWS for detecting chemical substances in air, water or biological liquids was proven. Theoretical computations and simulations found that the absorption signal is inversely proportional to the thickness of the fiber. These results were experimentally verified. A technique for flattening a central part of silver-halide (AgClxBr1-x) fibers was developed. Fibers of thickness down to 50 μ were produced, and tests proved their enhanced evanescent wave spectroscopy performance. This will be important, in particular, for water or soil pollution monitoring, where extremely small quantities of pollutants have to be detected in a solution.

Original languageEnglish
Pages (from-to)189-195
Number of pages7
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 1999
EventProceedings of the 1999 Infrared Optical Fibers and their Applications - Boston, MA, USA
Duration: 21 Sep 199922 Sep 1999


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