Low-loss GeO_2 optical waveguide fabrication using low deposition rate rf sputtering

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Abstract
Low-loss GeO2 thin-film optical waveguides have been prepared using rf reactive sputtering with a GeO2 target, and the propagation properties of the waveguides prepared over a wide range of fabrication conditions have been investigated. We have found that the waveguide attenuation dramatically decreased when a very low deposition rate of rf reactive sputtering in an argon–oxygen atmosphere was used in conjunction with appropriate annealing. In particular, 3800-Å thick GeO2 thin-film optical waveguides have been prepared with propagation losses 0 mode at a wavelength of 0.63 μm. The average refractive index of the GeO2 films was measured to be 1.6059 at λ = 5461 Å by an ellipsometer technique in good agreement with measurement on bulk materials. Propagation losses have also been measured at different wavelengths, which shows that GeO2 thin-film optical waveguides could be used over a very wide wavelength range from the visible to the near infrared.