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...

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Bibliographic Details
Published in:Applied optics (2004) 2008-05, Vol.47 (13), p.2357-2360
Main Authors: Hahn, Julia, Rüter, Christian E, Fecher, Frank, Petter, Jürgen, Kip, Detlef, Tschudi, Theo
Format: Article
Language:English
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Summary: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.
ISSN:1559-128X
DOI:10.1364/AO.47.002357