Abstract
SiO2-GeO2 glass films were deposited on a fused silica substrate by rf magnetron sputtering method. The rf power to the target and to the substrate along with the O2 partial pressure were changed. The refractive index of the films was measured by a prism coupler method. The GeO2 concentration in the films was determined by Inductively Coupled Plasma (ICP) optical emission spectroscopy. The internal stress of the films was derived from Stoney's equation. As the rf power to the target and to the substrate increased and the O2 partial pressure decreased, the refractive index of as-deposited films increased regardless of the GeO2 concentrations in films. These changes were considered to be caused by the difference in the oxidation state of the films due to deposition conditions. Therefore, oxygen annealing of the films has been investigated to supplement oxygen-deficient defects in SiO2-GeO2. The fluctuation of the refractive index of the films fell below the order of 4×10-4 by annealing in an O2 atmosphere for 3h at temperatures of 1100°C or higher. The optical attenuation of the waveguide was less than 7dB/m at 1300nm and 1550nm, which is sufficiently low for an optical waveguide.
