Enhanced acousto-optic properties at 1.55 µm wavelength from (As₂S₃)_100-x(Te₂S₃)_x chalcogenide glasses via tailoring of the network structure

Chalcogenide glasses (ChGs) attract attention for their excellent acousto-optic (AO) properties and broad applications in optical information processing. Te-based ChGs often have a high refractive index and large glass-forming region, suitable for high-performance AO devices. However, the correlation between composition, structure, and AO properties of As-S-Te ternary glasses is unclear, limiting their AO device applications. Here, the influence of Te₂S₃ content on optical, thermo-mechanical and AO properties of (As₂S₃)_100-x(Te₂S₃)_x glasses is investigated. Appropriate Te₂S₃ introduction induces the transformation from AsS₃ pyramids into AsS₂Te mixed pyramidal units, enhancing the AO figure of merit (<i>M₂</i>). Excessive Te₂S₃ content replaces strong covalent As-S bonds with weaker As-Te bonds, leading to adverse effects such as the increase of acoustic attenuation (<i>α</i>) and thermo-optical coefficient (<i>dn</i>/<i>dT</i>) and the decrease of laser-induced damage threshold (<i>LIDT</i>). This work provides theoretical guidance and an experimental basis for optimizing the composition design of As-S-Te glasses and fabricating high-performance AO devices.