Ultra-thin plasmonic metasurfaces based on carbon nanomembranes

Summary form only given. Metasurfaces have been established as a viable platform for flat optical devices [1]. However, the optical metasurfaces realized so far were situated on a substrate having macroscale thickness. Naturally, substrates can alter the properties of the metasurfaces undesirably. They do not only degrade the ultra-thin nature of metasurfaces but can also create additional loss channels such as reflections. Consequently, a variety of platforms were suggested in order to create substrate-free metasurfaces [3]. However, none of the approaches demonstrated so far allows for the realization of optical metasurfaces with nanoscale thickness. Here, we experimentally demonstrate ultra-thin plasmonic metasurfaces consisting of square arrays of U-shaped gold nano-resonators [2] situated on Carbon Nanomembranes (CNMs) with a thickness of only 1.2 nm. Carbon nanomenbranes belong to the family of two-dimensional materials and they have insulating properties. Their thickness can be adjusted (0.5 to 3 nm) by the choice of employed precursor molecules [4].