High-contrast waveguides in sputtered pure TeO2 glass thin films

We present a technological approach to the realization of channeled optical waveguides, starting from reactively sputtered tellurite glass thin films, grown on silica-coated 4” Si wafers. In particular, optical lithographic process and etching recipes have been developed to overcome the solubility of TeO2 films in aqueous solutions, and to process them into high-index contrast structures with minimized post-etch roughness. Optical tests on preliminary rib waveguide geometries feature 6.3 dB/cm propagation loss for fundamental TE mode at λ = 1.5 μm.