Metallic Metasurfaces for Light Absorbers

Multi-band light perfect absorption by all-metal resonant structure is of particular interest for applications in a wide variety of technologies. Here, we propose and demonstrate a new strategy for achieving multi-band light absorber based on the metallic sub-wavelength structure, which consists of a hexagonally packed nanoring-nanodisk composite array on an opaque metal substrate. By introducing asymmetry to the nanoring-nanodisk hybrid system, new absorption bands emerge. The optical properties are enabled by strong plasmon resonances of the metallic resonators and their near-field coupling effects. Designing such nanostructures is a promising route for all-metal multi-band light absorption platform, which can be used as absorption filters, photo-thermal therapy, multispectral thermal emitters, and plasmonic biosensors.