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Proceedings Paper

Fibre optic implementation of evanescent wave cavity ring-down spectroscopy for chemical detection
Author(s): Jonathan D. Fisk; Neil W. Hayes; Daniel Barnett; Mark Farries; Karen M. Tasker; Andrew M. Shaw
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Paper Abstract

A fibre optic platform has been fabricated for the field deployment of evanescent wave cavity ring-down spectroscopy with an absorbance sensitivity of 5 ppm. An optical cavity is fabricated by depositing high-reflectivity mirrors onto each end of the fibre and the evanescent field is exposed to the sample in a tapered region of the cavity. The decay time, τ, is dominated by the propagation loss of the radiation in the fibre optic and the loss of the tapered region. The multi-pass configuration can detect molecules adsorbing to the surface of the tapered region if they absorb radiation at the wavelength of the laser. An indicator molecule has been tethered to the glass surface to produce a colour change in response to the bulk pH producing an optical pH sensor with a sensitivity of 0.01 pH units. The fibre cavities have potential to form an optical sensor network to detect target molecules with presumptive detection on functionalised fibre surfaces.

Paper Details

Date Published: 28 October 2005
PDF: 8 pages
Proc. SPIE 5990, Optically Based Materials and Optically Based Biological and Chemical Sensing for Defence II, 59900T (28 October 2005); doi: 10.1117/12.634313
Show Author Affiliations
Jonathan D. Fisk, EvanesCo Ltd. (United Kingdom)
Neil W. Hayes, EvanesCo Ltd. (United Kingdom)
Daniel Barnett, EvanesCo Ltd. (United Kingdom)
Mark Farries, EvanesCo Ltd. (United Kingdom)
Karen M. Tasker, EvanesCo Ltd. (United Kingdom)
Andrew M. Shaw, EvanesCo Ltd. (United Kingdom)
Univ. of Exeter (United Kingdom)

Published in SPIE Proceedings Vol. 5990:
Optically Based Materials and Optically Based Biological and Chemical Sensing for Defence II
Anthony W. Vere; John C. Carrano; Arturas Zukauskas; James G. Grote; Francois Kajzar, Editor(s)

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