Paper
28 October 2005 Fibre optic implementation of evanescent wave cavity ring-down spectroscopy for chemical detection
Jonathan D. Fisk, Neil W. Hayes, Daniel Barnett, Mark Farries, Karen M. Tasker, Andrew M. Shaw
Author Affiliations +
Proceedings Volume 5990, Optically Based Materials and Optically Based Biological and Chemical Sensing for Defence II; 59900T (2005) https://doi.org/10.1117/12.634313
Event: European Symposium on Optics and Photonics for Defence and Security, 2005, Bruges, Belgium
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.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jonathan D. Fisk, Neil W. Hayes, Daniel Barnett, Mark Farries, Karen M. Tasker, and Andrew M. Shaw "Fibre optic implementation of evanescent wave cavity ring-down spectroscopy for chemical detection", Proc. SPIE 5990, Optically Based Materials and Optically Based Biological and Chemical Sensing for Defence II, 59900T (28 October 2005); https://doi.org/10.1117/12.634313
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KEYWORDS
Molecules

Absorbance

Fiber optics

Mirrors

Sensors

Optical resonators

Silica

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