title: Sensitivity enhancement of integrated optical sensors by use of thin high-index films.
abstract: The proportion of power carried in the superstrate medium by the guided modes of integrated optical waveguides can be increased by the addition of a thin high-index film. Enhanced refractive-index sensing is demonstrated with channel waveguide Mach-Zehnder interferometers with Ta(2)O(5) overlays. Sensitivity increases by a factor greater than 50, and a detection limit better than 5 x 10(-7) is obtained. This approach is broadly applicable to sensing at waveguide surfaces where the strength of evanescent fields dictates performance.
authors.affiliation: Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ United Kingdom. grq@orc.soton.ac.uk
authors.forename: G R
authors.initials: GR
authors.lastname: Quigley
authors.forename: R D
authors.initials: RD
authors.lastname: Harris
authors.forename: J S
authors.initials: JS
authors.lastname: Wilkinson