Guest Editor: Prof. Din Ping Tsai, City University of Hong Kong, China; Prof. Shumin Xiao, Harbin Institute of Technology, Shenzhen, China

Cover story: Gu ZF, Gao YX, Zhou KS et al. Surface-patterned chalcogenide glasses with high-aspect-ratio microstructures for long-wave infrared metalenses. Opto-Electron Sci 3, 240017 (2024).

Thermal imaging, which captures longwave infrared (LWIR) radiation from room- temperature objects, plays a crucial role in applications such as lowlight vision, medical diagnostics, and homeland security. A constant objective for thermal imaging optical systems is to become more compact and lightweight, which is highly desired for emerging technologies like self-driving cars and drone vision. All- dielectric metalenses offer a promising solution, bridging the real world and thermal imaging space in a light way. Chalcogenide glasses, also known as black diamond, are particularly suited for LWIR applications due to their exceptional wideband transparency and stable thermo-optical performance, which can be processed in various ways, including drawing into optical fibers, molding into lenses, owing to their amorphous nature. However, the surfaces of chalcogenide glasses remain a rarely explored dimension for chalcogenide glass engineering. In this study, the authors introduce a novel method for fabricating LWIR metalenses by directly patterning the chalcogenide glass surface with high-aspect-ratio microstructures using conventional microfabrication techniques. The resulting ultrathin, all- chalcogenide metalenses consist of a monolithic array of micropillars, each only eight micrometers high, on the chalcogenide glass surface, which demonstrate efficient LWIR wavefront control and deliver remarkable thermal imaging performance. This work paves the way for the development of compact optical meta-devices integrated on chalcogenide glass surfaces for LWIR light field manipulation.