Study of refractive index of GeO_2:SiO_2 mixtures using deposited-thin-film optical waveguides

Refractive indices of deposited thin films of amorphous GeO2:SiO2 mixtures were determined by multimode optical waveguide measurement techniques at four different wavelengths and used to characterize waveguide properties as a function of material composition. The results indicate that the refractive index varies linearly with the mole fraction of GeO2 in the guide, while wavelength dispersion increases with heavier GeO2 dopant concentrations. This is consistent with previously reported findings for bulk samples and suggests that linear variation of the film’s compositional content is a viable method for obtaining refractive indices and dispersive properties needed to interface with other optical devices in integrated optics-type applications.