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International audienceVariable angle spectroscopic ellipsometry technique was used to characterize optical functions of chalcogenide glasses from Ge-​As-​Te system in broad spectral range (300 nm-​20 μm)​. Measured real and imaginary parts of pseudodielec. function were modeled with Cody-​Lorentz approach and Sellmeier equation. Very good agreement between exptl. measured and modeled imaginary and real parts of pseudodielec. functions leads to precise detn. of optical functions (refractive index, extinction coeff.) of studied Ge-​As-​Te glasses in extremely broad spectral range covering UV-​Vis-​NIR-​MIR. The method is generally applicable for other glasses and amorphous materials

Amorphous thin films from Ge-As-Te system were prepared by pulsed laser deposition to study their intrinsic photostability, morphology, chemical composition, structure and optical properties. Photostability of fabricated layers was studied by spectroscopic ellipsometry within as-deposited as well as relaxed (annealed) layers. For irradiation, laser sources operating at three wavelengths in band gap region of the studied materials were employed. The results show that lowest values of photorefraction accompanied with lowest changes of band gap values were exhibited by Ge20As20Te60 thin films, which are therefore considered as the layers with highest photostability in relaxed state. The structure of the films is discussed based on Raman scattering spectroscopy data.

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As_xTe_100-x amorphous thin films were fabricated by a pulsed laser deposition technique with the aim of finding photostable layers in as-deposited but preferably in relaxed (annealed) state. Photostability was studied in terms of the films' stability of refractive index and bandgap under near-bandgap light irradiation. As₄₀Te₆₀ and As₅₀Te₅₀ layers were found to be photostable in both as-deposited as well as relaxed states. Moreover, As₅₀Te₅₀ layers present the lowest surface roughness. These characteristics make pulsed-laser-deposited As₅₀Te₅₀ thin films promising for applications in nonlinear optics.