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

Abstract The laponite films elaboration is based on the sol–gel process and dip-coating technique. The films are dried at 120°C and heat-treated at higher temperature up to 600°C without deterioration of their quality. Three micrometer thick and crack-free films are obtained in only one coating by dipping a substrate into a well-controlled viscous solution. By this way 9 μm 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 the powder indicate water removal phenomenon at different annealing temperatures. These results are correlated with X-ray diffraction (XRD) analyses to explain preferential orientation and densification of the 600°C heat-treated layer. This structural behavior involves optical birefringence and refractive index increase of the film. Potentialities to use laponite films in planar optical waveguide field are presented.