Flannery, D.James, Stephen W.Tatam, Ralph P.Ashwell, Geoffrey J.2011-06-032011-06-031999-12-20Damian Flannery, Stephen W. James, Ralph P. Tatam, and Geoffery J. Ashwell, Fiber-optic chemical sensing with Langmuir-Blodgett overlay waveguides, Applied Optics, Vol. 38, Issue 36, pp. 7370-7374 (1999)0003-6935http://dx.doi.org/10.1364/AO.38.007370http://dspace.lib.cranfield.ac.uk/handle/1826/5454Fiber-optic chemical sensing has been demonstrated with a side-polished single- mode optical fiber, evanescently coupled to chemically sensitive Langmuir- Blodgett (LB) overlay waveguides. The sensors exhibit a channel-dropping response centered on a wavelength that is dependent on the thickness and the refractive index of the overlay waveguide. It has been shown that pH-sensitive organic dyes proved to be suitable materials fur the formation of an overlay waveguide whereas LB deposition provides the required thickness control. A theoretical model of the sensor response, based on the Kramers-Kronig relations and phase matching of the guided modes within the optical fiber and overlay waveguide, shows good agreement with experimental results.en-UKThis paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=ao-38-36-7370 Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.absorption lineArticle