Characteristics of laser-densified and conventionally heat treated sol-gelderived silica-titania films

Thin films of various compositions in the system SiO2-TiO2 were prepared by the sol-gel method, with the effects of laser-densification and heat treat ment being studied. The etch rate of the resultant coating films was found to change by a factor of almost 1000 for various heat treatment conditions in the temperature range 600 similar to 800 degreesC. By combining laser si ntering of selected areas and chemical etching techniques, the large differ ence between the etch rates of densified and undensified coatings can be us ed to produce channel waveguide structures. The etched coatings were charac terized by X-ray diffraction, Fourier transform infrared spectra and micro- Raman spectra with these studies indicating that crystallization occurs in the region of laser scanning with dimensions corresponding approximately to the width of the beam used. (C) 2001 Elsevier Science B.V. All rights rese rved.