Investigation of acousto-optic properties of tellurium-based glasses for infrared applications

We examined the physical properties of infrared optical glasses composed of tellurium, germanium, selenium, sulfur and silicon. In particular, we measured optical, acoustic and photoelastic parameters of the following alloy compounds: germanium–selenium–tellurium (Ge–Se–Te), germanium–selenium–sulfur–tellurium (Ge–Se–S–Te), germanium–silicon–tellurium (Ge–Si–Te) and silicon–tellurium (Si–Te). Like single-crystal tellurium, the glasses demonstrate good acousto-optic (AO) diffraction efficiency and have reasonable optical transparency in a wide spectral region covering wavelengths from 1.5 to 20 μm. The optical, acoustic and photoelastic properties of the tellurium-based compounds were measured using infrared lamp sources of radiation as well as He–Ne and CO₂ lasers. In this paper, we report on the optical, acoustic and photoelastic parameters of a selection of these compounds and discuss the advantages and disadvantages of using these glasses for AO device applications. We also present the measured characteristics of an AO cell fabricated in a Si₂₀Te₈₀ glass material which exhibited high optical uniformity and long-term chemical stability. (paper)