A thick sol-gel inorganic layer for optical planar waveguide applications

The laponite films elaboration is based on the sol-gel process and dip-coat ing technique. The films are dried at 120 degreesC and heat-treated at high er temperature up to 600 degreesC without deterioration of their quality. T hree micrometer thick and crack-free films are obtained in only one coating by dipping a substrate into a well-controlled viscous solution, By this wa y 9 mum high quality thick films have been prepared using three successive coatings and adapted heat treatment. These films exhibit light waveguiding properties. Differential thermal analysis (DTA) measurements conducted on t he powder indicate water removal phenomenon at different annealing temperat ures, These results are correlated with X-ray diffraction (XRD) analyses to explain preferential orientation and densification of the 600 degreesC hea t-treated layer. This structural behavior involves optical birefringence an d refractive index increase of the film. Potentialities to use laponite fil ms in planar optical waveguide field are presented. (C) 2001 Elsevier Scien ce B.V. All rights reserved.