Thermally matched chalcogenide glasses with high refractive index contrast for infrared graded‐index lenses
Qian Chen, Anping Yang, Cheng Ma, Zhijie Yang, Zhijie Yang, Zijun Liu, Xiang Shen, Zhiyong Yang, Zhiyong Yang
Abstract
Abstract Infrared graded‐index (GRIN) lenses are desirable for realizing miniaturization and lightweight of infrared imaging systems. Chalcogenide glasses have excellent infrared transparency, good rheological property, and large refractive index range, making them preferred materials for infrared GRIN lenses. In this work, aiming to find thermally matched chalcogenide compositions with high refractive index contrast for preparing GRIN glasses by the stacking diffusion approach, we investigated characteristic temperature, thermal expansion coefficient and refractive index of Ge‐As‐Se and Ge‐As‐Se‐Te glasses, optimized the glass compositions, and evaluated the feasibility of preparing GRIN glass using the optimized chalcogenide glass powders. It is found that Ge 20 As 20 Se 20 Te 40 and Ge 12 As 22 Se 66 glasses have similar softening temperature (247°C vs. 249°C), reasonably difference of thermal expansion coefficient (3.8 ppm/K), and large refractive index contrast (∼.48). The glass powders with composition xGe 20 As 20 Se 20 Te 40 ‐(1‐x) Ge 12 As 22 Se 66 can be hot‐pressed into glass disks with good transmittance at the same temperature and pressure. Graded refractive index profile is formed near the interface between the layers after the co‐pressed glass is thermally treated. These results demonstrate the prospect of the compositions for preparing infrared GRIN glasses.