Effect of temperature on the reflective index dispersion of AsXS1−X glasses


Purpose. The purpose of this research was to prepare AsXS1−X glasses and to study concentration and temperature dependences of their refractive index.
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. It was found that the refractive index of the studied materials n at a fixed wavelength λ decreases with increasing temperature, dn/dT = −1, 2… − 10, 5 · 10−5 K−1 depending on the composition.
Conclusions. The experimental results of n(λ) of AsXS1−X glasses were described in terms of the Wemple – DiDomenico single effective oscillator model. Based on the experimental results, atomic refractions and the polarizability coefficient of glasses of the AsXS1−X system were calculated, and their temperature behavior and concentration dependence were explained. It was concluded that thermal expansion coefficient makes the main contribution to the value of the temperature dependence of the refractive index

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