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Proceedings Paper

Fiber optic pH sensors using thin-film Langmuir-Blodgett overlay waveguides on single-mode optical fibers
Author(s): Damian Flannery; Stephen W. James; Ralph P. Tatam; Geoffrey J. Ashwell
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Paper Abstract

A fiber-optic pH sensor is demonstrated using thin film Langmuir-Blodgett (LB) films to form a single-mode planar waveguide, evanescently coupled to a side-polished single- mode optical fiber. The LB technique shows two distinct advantages in the fabrication of such sensors, the ability to control the overlay waveguide thickness to a single molecular layer (approximately 3 nm) and also, as the materials used are organic, the ability to engineer specific materials for different sensing purposes. The response of the sensor is also investigated through changes in the overlay refractive index, caused by changes in its absorption spectrum via a simple Kramers-Kronig model. The model is shown to be able to predict the response of the sensor.

Paper Details

Date Published: 1 October 1997
PDF: 9 pages
Proc. SPIE 3133, Optical Thin Films V: New Developments, (1 October 1997); doi: 10.1117/12.279109
Show Author Affiliations
Damian Flannery, Cranfield Univ. (United Kingdom)
Stephen W. James, Cranfield Univ. (United Kingdom)
Ralph P. Tatam, Cranfield Univ. (United Kingdom)
Geoffrey J. Ashwell, Cranfield Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 3133:
Optical Thin Films V: New Developments
Randolph L. Hall, Editor(s)

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