Optical waveguiding in amorphous tellurium oxide thin films

Abstract Optical waveguiding characteristics of amorphous TeO2−x films deposited by reactive sputtering under different O2:Ar gas mixtures are investigated on fused quartz and Corning glass substrates. Infra-red absorption band in the range 641–658 cm−1 confirmed the formation of a TeO bond, and a 20:80 O2:Ar gas mixture ratio is found to be optimum for achieving highly uniform and transparent films at a high deposition rate. As grown amorphous films exhibited a large band gap (3.76 eV); a high refractive index value (2.042–2.052) with low dispersion over a wide wavelength range of 500–2000 nm. Optical waveguiding with low propagation loss of 0.26 dB/cm at 633 nm is observed on films subjected to a post-deposition annealing treatment at 200 °C. Packing density and etch rates have been determined and correlated with the lowering of optical propagation loss in the annealed films.