Large‐Area, Broadband, Wide‐Angle Plasmonic Metasurface Absorber for Midwavelength Infrared Atmospheric Transparency Window

Abstract High performance broadband absorbers in the midinfrared atmospheric transparency windows are of great importance in various applications, such as energy harvesting, photodetection, radiative cooling, and stray light elimination. In recent years, great efforts have been made to develop absorbers using plasmonic nanostructured resonators in the infrared regime. Although these approaches promise distinct advantages in performance enhancement, they still suffer several obstacles, e.g., limitations on sample size, bandwidth, and fabrication throughput. Here, a large‐area broadband wide‐angle plasmonic metasurface absorber with nearly perfect absorption over the range of midwavelength infrared atmospheric transparent window (3–6 µm) is proposed and experimentally demonstrated. The metasurface absorber is basically comprised of a monolayer of sub‐micrometer‐sized polystyrene spheres self‐assembled on an opaque metallic substrate and coated with metal–insulator–metal three‐layer thin film, and fabricated by using simple, low‐cost self‐assembly techniques. Numerical simulation analyses not only corroborate the experimental observations, but also discover that such broadband absorption effect is attributed to hybrid plasmonic multiple resonances. The combination of the significant light absorption effect, compact design, and high‐yield self‐assembly fabrication process suggests that the proposed absorber has wide prospect application in integrated optical and optoelectronic systems.