Sputtered Stoichiometric TeO2 Glass Films: Dispersion of Linear and Nonlinear Optical Properties

We report on the optical characterization of TeO2 amorphous films deposited by radio-frequency (rf) reactive sputtering. X-ray diffraction, electronic microscopy, and Rutherford backscattering analysis have been performed in order to assess the structural and compositional properties of the samples. The linear optical characterization has been performed by variable angle spectroscopic ellipsometry at wavelengths between 260 and 1700 nm, leading to determination of the dispersion of the complex refractive index for sputtered tellurium dioxide. In the spectral range of transparency, between 1700 and 500 nm, refractive index values ranging from 2.05 to 2.16 have been obtained. The dispersion of the complex third-order nonlinear optical coefficient of the sample has been evaluated in the near-infrared spectral range by third harmonic generation measurements. The out-of-resonance value of the χ(3) coefficient for TeO2 is in the range between 1.2×10−12 and 1.4×10−12 esu. The conjugation of optical transparency, high nonlinear refractive index and the possibility of growing films of good optical quality, make rf sputtered TeO2 a promising material for the implementation of devices for the processing of optical communication signals