MICROSTRUCTURAL AND OPTICAL-PROPERTIES OF SOL-GEL SILICA-TITANIA WAVE-GUIDES

Two micron silica-titania coatings made by single step sol-gel dip-coa ting were prepared as planar waveguides. Acid catalyzed solutions of m ethyltriethoxysilane (MTES) mixed with tetraethoxysilane (TEOS) and te trabutoxytitanate were used as precursors. Purely inorganic and crackf ree silica-titania coatings were obtained after annealing at 500 degre es C. The waveguides had propagation losses, 0.3 dB/cm, of the same or der as thin silica-titania films prepared without MTES, Films were stu died by infrared spectroscopy, Rutherford backscattering spectrometry, nuclear reactions analysis and elastic recoil detection analysis. The waveguide structural composition after annealing at 500 degrees C was found to be similar to MTES and TEOS derived silica-titania coatings. The waveguides were characterized by measuring refractive index, poro sity and shrinkage, with thermal treatment. The MTES derived films sho wed a higher shrinkage during annealing but the same refractive index and porosity as the TEOS derived waveguides. (C) 1997 Elsevier Science B.V.