title: Fiber-optic chemical sensing with langmuir-blodgett overlay waveguides.
abstract: Fiber-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 for 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.
authors.affiliation: Centre for Photonics and Optical Engineering, School of Mechanical Engineering, Cranfield University, Cranfield, Bedford MK43 OAL, UK.
authors.forename: D
authors.initials: D
authors.lastname: Flannery
authors.forename: S W
authors.initials: SW
authors.lastname: James
authors.forename: R P
authors.initials: RP
authors.lastname: Tatam
authors.forename: G J
authors.initials: GJ
authors.lastname: Ashwell