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Virtual Journal for Biomedical Optics

Virtual Journal for Biomedical Optics


  • Editor: Gregory W. Faris
  • Vol. 1, Iss. 6 — Jun. 13, 2006

Evanescent-wave optical Cr VI sensor with a flexible fused-silica capillary as a transducer

Shiquan Tao and T. V. S. Sarma  »View Author Affiliations

Optics Letters, Vol. 31, Issue 10, pp. 1423-1425 (2006)

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A light-guiding, flexible fused-silica (FFS) capillary has been used in designing an optical fiber Cr VI sensor for monitoring Cr VI ions in water samples. The FFS capillary is similar to a conventional silica optical fiber in that it can guide light in the wavelength region from the UV to the near I R but different from a conventional optical fiber in that it is a tubular waveguide. The inner surface of the FFS capillary is fused silica, which one can modify to design an optical fiber chemical sensor. The FFS capillary has a cladding layer plus a protective polymer coating on its outside surface. The cladding layer ensures the ability of the FFS capillary to guide light. The protective coating increases the FFS capillary’s mechanical strength and makes it robust for practical applications. Compared with conventional silica optical fibers, it is much easier and more feasible to use this FFS capillary to fabricate long-path (tens of meters to thousands of meters) evanescent-wave based chemical sensors. We describe a Cr VI sensor based on the intrinsic evanescent-wave absorption by Cr VI ions in a water sample filled inside the capillary as an example of use of a FFS capillary in chemical sensor design. This simple sensor, using a 30 m light-guiding FFS capillary as a transducer, has the capability of detecting as little as 31 parts in 10 9 of Cr VI in a water sample, which is close to the detection limit of some sophisticated, expensive analytical instruments.

© 2006 Optical Society of America

OCIS Codes
(000.1570) General : Chemistry
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(160.4670) Materials : Optical materials
(230.7370) Optical devices : Waveguides

ToC Category:
Integrated Optics

Original Manuscript: December 19, 2005
Revised Manuscript: February 3, 2006
Manuscript Accepted: February 7, 2006

Virtual Issues
Vol. 1, Iss. 6 Virtual Journal for Biomedical Optics

Shiquan Tao and T. V. S. Sarma, "Evanescent-wave optical Cr VI sensor with a flexible fused-silica capillary as a transducer," Opt. Lett. 31, 1423-1425 (2006)

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