Preparation and properties of organically modified sol-gel silica/titania optical waveguides

Silica/titania optical waveguides have been prepared by the sol-gel technique using y-Glycidoxypropyltrimethoxysilane and tetrapropylorthotitanate as the starting materials. Scanning electron microscopy, atomic force microscopy, thermal gravimetric analysis, differential thermal analysis, and UV-Visible spectroscopy have been used to characterize the morphology, the optical and structural properties of the waveguide films. The waveguides are also characterized by measuring their refractive index, thickness, and propagation loss as a function of titanium content and thermal treatment. The obtained results show that after an annealing at 500°C or above, an inorganic silica/titania crack-free film could be obtained. The single layer spin-coated film has high transparency in the visible range and is more than 0.5 micron thick. The propagation loss of the waveguide films was also estimated by using the scattered-light measurement method and was found to be around 1.0 dB/cm at the wavelength of 632.8 nm.