Abstract
Compact and lightweight optical components are highly desirable for long-wave infrared (LWIR) thermal imaging, whereas conventional refractive lenses are typically bulky and difficult to miniaturize, limiting their use in next-generation thermal imaging systems. Here, we report centimeter-scale metalenses directly patterned on chalcogenide glass (As2Se3) substrates for LWIR thermal imaging. Inspired by multilevel diffractive lenses, the metalens is designed with concentric ring arrays of micropillars. The designed metalens exhibits a theoretical relative focusing efficiency of 94.9% and an absolute focusing efficiency of 69.1% without considering backside reflection. By combining ultraviolet contact lithography with plasma etching, we fabricate an all-chalcogenide glass metalens with a diameter of 1 cm. The asfabricated As2Se3 micropillars have a height of 8 μm and diameters ranging from 2 μm to 3.96 μm, showing good structural uniformity over the centimeter-scale aperture. Optical measurements demonstrate that the fabricated metalens efficiently focuses a 9.78 μm quantum cascade laser beam and enables clear thermal imaging of a heated soldering iron, highlighting the potential of chalcogenide glass as a promising platform for LWIR meta-optics.