IR reflectivity spectra analysis of solgel SiO₂-TiO₂-GeO₂ coatings in hollow waveguide

It is shown that the IR reflectivity of SiO₂-TiO₂ gel glass coating was very low at the wave-length of CO₂ laser (10.6 μm) although the content of TiO₂ was as high as 80%. In terms of SiO₂-TiO₂-GeO₂ gel glass coating, its peak gradually moved to the wavelength of CO₂ laser and the reflectivity finally reached 21% at 106 μm when the content of GeO₂ increased from 20 to 30%. However, when the content of GeO₂ was beyond 35% the IR reflectivity almost reached zero. Therefore, the gel glass coating of 40SiO₂-30TiO₂-30GeO₂ is a good candidate material in application.