GEO2-SIO2 THIN-FILMS FOR PLANAR WAVE-GUIDE APPLICATIONS

Various thin films of germanium silicate glass with high germania content have been fabricated by a sol-gel method. After densification, these films have a high optical quality and can be used as planar waveguides. The densification behavior of these films was studied by measurements of the index of refraction, as a function of heat treatment temperatures, using ellipsometry. The relationship of refractive index versus GeO2 content follows the additive Lorentz-Lorenz model. Waveguiding Raman spectroscopy suggested the formation of Si-O-Ge linkages in these films without phase segregation. Various waveguide propagation characteristics, at 632.8 nm, were studied using a prism coupling technique. The propagation loss rate of a 50GeO(2)0-50SiO(2) glass waveguide was measured as 3.31 dB/cm.