Tellurium oxide is a promising optical material, conjugating transparency in the infrared with high refractive index, low chromatic dispersion with strong nonlinear response, elevated acousto-optic figure of merit and rare earth doping capability. Reactive sputtering is a suitable technique to obtain thin films of pure TeO₂ glass, with tunable stoichiometry, without the need for added components to help vitrification. We report on the growth of tellurite thin films, on the linear and non-linear optical characterization and on the process technology to implement high-contrast planar optics.