IR spectra analysis of SiO₂ - TiO₂ - GeO₂ gel glass of CO₂ laser transmitting hollow waveguide

Both titanium and germanium were introduced into silicon dioxide system by sol-gel method to move its region of anomalous dispersion caused by IR resonance absorption towards the wavelength of CO₂ laser. It is indicated by IR absorption spectra that as the content of SiO₂ decreases in this glass system TiO₂ and GeO₂ tends to exist in their own phases. As for the gel glass with a composition of 40SiO₂ · 30TiO₂ · 30GeO₂, when the temperature is below 600°C, germanium atoms exist mainly in Ge-O-Ge bonds. With the temperature increasing from 800°C to 1000°C, titanium atoms in Si-O-Ti bonds almost transform into Ti-O-Ti bonds. Furthermore, a large number of Si-O-Ti and Si-O-Ge bonds formed when the temperature approaches 800°C, which makes a notable IR absorption band round the wavelength of CO₂ laser. Therefore, sol-gel based SiO₂ - TiO₂ - GeO₂ gel glass is a candidate material for CO₂ laser hollow waveguide.