Modal filtering in nulling interferometer is based on the capability of single-mode waveguides to transmit only one complex amplitude function to eliminate virtually any perturbation of the interfering wavefronts. In this letter, we focus on realizing single-mode waveguide of chalcogenide glasses in the thermal infrared range 6–20 \mu m by burying a GASIR (Ge-As-Se) fiber core in the substrates of As-Se-S glasses system. To match the single-mode operation, GASIR fiber core of about 15-μm diameter is drawn, the fiber core is buried into As-Se-S substrates by heating two kinds of glasses to a suitable temperature. The propagation mode is tested by guiding a CO2 laser emitting at 9.3 μm into the waveguide. Single-mode out coming signal is obtained by an infrared camera.

采用熔融淬冷法制备了新型远红外Te基硫系玻璃Ge20-xTe65Se15Snx (x=0，2，4)。在Ge-Te-Se玻璃的基础上，通过引入重金属Sn,研究其对玻璃组成、结构和性能的影响。测试了样品的中红外热成像、X射线衍射（XRD）图谱、差热分析曲线(DSC)、可见/近红外吸收光谱、红外透射光谱。利用经典的Tauc方程计算了样品的光学带隙，根据金属标准和能量带隙理论讨论了玻璃光学带隙与组分变化的关系。分析结果表明，Ge-Te-Se-Sn玻璃具有良好的热稳定性，随着Sn的引入，玻璃的光学带隙减小，短波吸收截止边发生红移，但玻璃的红外截止波长基本不变。 此外Sn可以有效减弱Ge-O杂质吸收峰的强度，提高玻璃红外透射性能。