Preparation and spectroscopic studies of sol-gel derived GeO ₂/organically modified silane hybrid materials for optical waveguides

GeC₂/organically modified silane organicinorganic hybrid materials derived by a sol-gel technique were studied for optical waveguide applications. Acidcatalyzed solutions, firstly, γ- glycidoxypropyltrimethoxysilane mixed with germanium isopropoxide, and secondly, methyltrimethoxysilane mixed with germanium isopropoxide were used as precursors. Optical and structural properties of the waveguide thin films prepared from the two types of sols were characterized by using the prism coupling technique, atomic force microscopy, thermal gravimetric analysis, UV-visible spectroscopy, and Fourier transform infrared. The obtained results indicate that in both cases, crack-free and highly transparent waveguide thin films with a thickness of more than 2-μm could be obtained by a single spin-coating process and at a low-temperature heat treatment of 100μC. A strong UV absorption region at short wavelength ∼ 200 nm, accompanied with a shoulder peaked at ∼240 nm, was also identified. It has been experimentally demonstrated that a channel waveguide structure could easily be fabricated from the hybrid sol-gel thin films by using reactive ion etching.