Recent advances in acousto-optic properties of chalcogenide glasses (invited)

Significance  With the rapid advancement of acousto-optic modulation technology towards higher frequencies, increased power handling, and broader spectral bandwidths, the limitations of traditional oxide glasses and crystals in terms of transmission range, acousto-optic figure of merit, and diffraction efficiency have become increasingly apparent. consequently, there is an urgent need to develop new materials with superior acousto-optic performance. Chalcogenide glasses, as a class of emerging substrate materials for optoelectronic devices, exhibit several advantageous properties, including high refractive index, broad infrared transmission window, low phonon energy, large optical nonlinearity, and highly tunable composition. These attributes render chalcogenide glasses ideal candidates for fabricating acousto-optic (AO) devices with high diffraction efficiency, low acoustic attenuation, and high laser-induced damage threshold. Building on this foundation, advancements in controlled crystallization strategies, the development of environmentally benign compositions, and breakthroughs in large-scale, high-homogeneity fabrication processes have significantly improved the mechanical strength, thermal stability, and environmental compatibility of chalcogenide glasses, thereby further expanding their application potential in areas such as acousto-optic modulation, infrared imaging, and optical communication. Therefore, in-depth investigations into key AO performance parameters—including the acousto-optic figure of merit, diffraction efficiency, and ultrasonic attenuation—as well as the correlations between chemical composition, microstructure, and degree of crystallization, are of great scientific significance. These studies not only help elucidate the structure–property relationships of such materials but also provide a robust theoretical framework and material basis for the development of next-generation high-performance infrared acousto-optic devices.

Progress  In recent years, research on chalcogenide glasses for AO applications has made systematic progress across multiple dimensions, including the expansion of material systems, enhancement of performance parameters, deepening of structural regulation mechanisms, and the development of new material forms.

　　Firstly, in terms of material systems, researchers have focused on three principal systems–sulfur-based, selenium-based, and tellurium-based glasses. Through multi-component doping and compositional optimization strategies, significant improvements have been achieved in key parameters such as the acousto-optic figure of merit (M₂), ultrasonic attenuation, and diffraction efficiency, laying a solid material foundation for advancing the performance of mid- and far-infrared AO devices.

　　Secondly, driven by environmental friendly and practical application demands, green and non-toxic glass systems (e.g., Ge–Sb–S, Ga–Sb–S, Ge–Sb–Se) are gradually replacing arsenic-containing compositions (e.g., Ge–As–S, Ge–As–Se). Notably, these new systems not only meet safety requirements but also outperform some traditional glasses in terms of AO performance, demonstrating promising application potential.

　　Furthermore, the introduction of controlled micro-crystallization strategies has opened new avenues for the comprehensive optimization of chalcogenide glasses. Through controlled precipitation of nanocrystals, synergistic regulation of thermal stability, mechanical strength, and acousto-optic properties has been realized, offering novel solutions for high-power and high-stability applications.

　　Finally, with the widespread application of high-resolution structural characterization techniques and first-principles calculations, the intrinsic relationships among composition, structure, and properties have become increasingly clear. This has laid a solid theoretical foundation for performance prediction and targeted material design.

　　In summary, research on the acousto-optic properties of chalcogenide glasses is evolving from basic material development to in-depth mechanism elucidation, from single-parameter optimization to multi-property synergistic design, and from experimental exploration to industrial application. These advances are propelling chalcogenide glasses toward a new stage of high performance, environmental friendliness, and engineering applicability in acousto-optic technologies.

Conclusions and Prospects  This paper systematically reviews the acousto-optic properties of three chalcogenide glass systems (sulfur-, selenium-, and tellurium-based) and their glass-ceramic systems, with particular emphasis on analyzing how compositional modifications and structural regulation strategies influence critical performance parameters including the acousto-optic figure of merit (M₂), acoustic attenuation (α), and diffraction efficiency (η). Table 1 summarizes the key acousto-optic parameters of these three chalcogenide glass systems and their corresponding glass-ceramics.

　　Based on the above analysis, future research into the acousto-optic performance of chalcogenide glasses can be further deepened in the following aspects:

　　1) Systematic Correlation of Composition-Structure-Property Relationships Advanced structural characterization techniques such as high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and nuclear magnetic resonance (NMR) should be employed to elucidate the bonding characteristics, covalent network configurations, and topological ordering in chalcogenide glasses. Combined with first-principles calculations, quantitative correlations between microstructural parameters (e.g., coordination number, unsaturated bond ratio, network connectivity) and acousto-optic performance metrics (e.g., acoustic velocity, photoelastic constant, refractive index) should be established. This will enable the development of a generalizable theoretical model for predicting acousto-optic properties, thereby creating a structure-property prediction framework that bridges glass composition design to performance optimization.

　　2) Enhanced Controllability of Glass-Ceramic Processes By developing tunable strategies that synergize thermal treatment and doping techniques, precise control over the crystallization kinetics can be achieved, allowing regulation of the size, density, and spatial distribution of nanocrystals within the glass matrix. This provides a foundation for optimizing the glass–crystal interface structure, improving the compatibility and structural stability at the amorphous–crystalline boundary, and ultimately enhancing acousto-optic performance while maintaining high mechanical strength.

　　3) Balancing High Performance and Environmental Materials Replacing toxic elements (e.g., As, Pb) traditionally used in chalcogenide glasses with environmentally benign alternatives (e.g., Ga, In, Bi) has become an urgent priority, without compromising optical transparency, thermal stability, or mechanical integrity. Experimental optimization of non-toxic element incorporation, guided by performance requirements, will facilitate the green transition of these material systems while preserving their acousto-optic performance.