Sol-gel processed silica/titania/y-glycidoxypropyltrimethoxysilane composite materials for photonic applications

Silica/titania/y-Glycidoxypropyltrimethoxysilane composite materials proces sed by the sol-gel technique were studied for photonic applications. Wavegu ide thin films with thickness more than 1.7 mu m were prepared by the sol-g el spin coating technique and low temperature heat treatment from this high titanium content composite materials. The films were analyzed by atomic fo rce microscopy (AFM), ellipsometry, differential thermal analysis (DTA), th ermal gravimetric analysis (TGA), UV-visible spectroscopy (UV-VIS), and Fou rier transform infrared (FT-IR) spectroscopy. It was observed that the film becomes thinner as the titanium contents increase. A change of the refract ive index through the range 1.52-1.61 at the optical wavelength of 633 nm w as achieved by varying the molar ratio between silica and titanium. A dense , low absorption, and high transparency in the visible range waveguide film s could be obtained at a low temperature. It was also noted that organic co mpounds in the film would decompose in the temperature range from 200 degre es C to 480 degrees C. Accordingly, purely inorganic silica-titania films w ith a thickness of about 0.7 mu m could also be obtained by a single-coatin g process, when the film was baked at a temperature of 500 degrees C or hig her. The waveguides properties and photonic applications of the composite m aterial sol-gel films were also investigated.