title: Measurement of the enhanced evanescent fields of integrated waveguides for optical near-field sensing.
abstract: The sensitivity of an integrated optical sensing device can be enhanced by coating it with a high refractive index layer, while both incoupled intensity and spatial resolution are maintained. The potential for enhanced sensing is demonstrated using titanium indiffused waveguiding structures in LiNbO(3) coated with a TiO(2) film. To the best of our knowledge, it could be measured for the first time that the outcoupled intensity at the surface was enhanced by a factor of 12-15 while keeping the penetration depth of the evanescent field constant of the order of only a few tens of nanometers. The evanescent fields of the guided modes were measured and characterized with a scanning near-field optical microscope and are in accordance with the numerical simulations.
authors.affiliation: Institute of Applied Physics, Technische Universität Darmstadt, Hochschulstrasse 6, 64289 Darmstadt, Germany. julia.hahn@physik.tu-darmstadt.de
authors.forename: Julia
authors.initials: J
authors.lastname: Hahn
authors.forename: Christian E
authors.initials: CE
authors.lastname: Rüter
authors.forename: Frank
authors.initials: F
authors.lastname: Fecher
authors.forename: Jürgen
authors.initials: J
authors.lastname: Petter
authors.forename: Detlef
authors.initials: D
authors.lastname: Kip
authors.forename: Theo
authors.initials: T
authors.lastname: Tschudi