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

Low-loss GeO(2) thin-film optical waveguides have been prepared using rf reactive sputtering with a GeO(2) 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-A thick GeO(2) thin-film optical waveguides have been prepared with propagation losses <0.7 dB/cm for the TE(0) mode at a wavelength of 0.63 microm. The average refractive index of the GeO(2) films was measured to be 1.6059 at lambda = 5461 A by an ellipsometer technique in good agreement with measurement on bulk materials. Propagation losses have also been measured at different wave-lengths, which shows that GeO(2) thin-film optical waveguides could be used over a very wide wavelength range from the visible to the near infrared.