Characterization of germanium-doped silica layers deposited by flame-hydrolysis

Abstract The optical properties of germanium-doped silica layers deposited by flame-hydrolysis have been investigated by analyzing the effective refractive indices of the modes using an inverse-WKB (Wentzel–Kramers–Brillouin) approach followed by an optimization algorithm. The shape obtained for the refractive index profile is consistent with the compositional and density characterization, performed by X-ray photoelectron spectroscopy (XPS) and X-ray reflectivity, respectively. We believe that the origin of the non-uniformity was the high-temperatures to which the as-deposited soot is subjected in order to obtain fully consolidated, high-optical quality films.