SPECTRAL DEPENDENCE OF TEMPERATURE INCREMENT OF REFRACTIVE INDEX OF As–S GLASSES

Abstract.

Purpose. The purpose of this research was to expand the study of the effect of temperature on the optical properties of AsXS1−x glasses and to compare the experimental data dn/dT = f(λ) with those calculated using Wemple and Di-Domenico single effective oscillator model. Methods. The refractive index was measured by a prism method. Plane parallel slabs with thicknesses of ∼1 mm were cut from synthesized bulk samples. The sample prisms had refracting faces with areas of 5×10 mm and angles between them of ∼ 10°-15°. The refracting angles of the prisms were determined on a LOMO G-1.5 goniometer. The temperature was measured with a copper-constantan thermocouple to within ±0.5 K. The error in the refractive index n over the entire observed spectral range was ±2·10–4. Results. The dispersion of the refractive index n(λ) of AsXS1−X glasses was studied in the concentration range from X = 0.20 to X = 0.40 of five samples in the temperature range from 80 to 370 K at wavelengths from 1.0 μm to 2.3 μm. The experimental results of n(λ) of AsXS1−X glasses were described in terms of the Wemple–Di-Domenico single effective oscillator model. The expression of the spectral dependence of the temperature increment of the refractive index (dn/dT) is obtained, according to which the spectral dependence of this parameter was calculated. Conclusions. Based on the experimental results, the concentration dependence of the refractive index are explained using the Lorentz-Lorentz formula. It is shown that dn/dT changes the sign in the region λ ∼ 0.96 μm, which agrees with the experimental data. In the area of transparency of the studied materials, dn/dT is negative. It was concluded that temperature change of the refractive index for As-S glasses depends mainly on the electron-phonon interaction, the magnitude of which decreases with increasing sulfur concentration

Keywords: glassy, synthesis, refraction, refractive index, single-oscillator model, energy of electronic oscillator, dispersion energy, temperature

https://doi.org/10.24144/2415-8038.2020.47.32-43