Measurement of the enhanced evanescent fields of integrated waveguides for optical near-field sensing.
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.
Hahn
Julia
J
Institute of Applied Physics, Technische Universität Darmstadt, Hochschulstrasse 6, 64289 Darmstadt, Germany. julia.hahn@physik.tu-darmstadt.de
Rüter
Christian E
CE
Fecher
Frank
F
Petter
Jürgen
J
Kip
Detlef
D
Tschudi
Theo
T