Random Graphene Metasurfaces: Diffraction Theory and Giant Broadband Absorptivity

Abstract

We introduce diffraction-theory-inspired analytic description of the metasurface comprising an array of graphene subwavelength hemispheres. Our theory describes light interaction with the random metasurface, in which the periodicity is broken by accidentally damaged meta-atoms in the nodes of a two-dimensional periodic lattice. Both numerical modeling and experiment show that such a nm-thin metasurface possesses giant broadband absorption in the THz spectral range that remains intact even when a substantial portion of meta-atoms, i.e. graphene hemispheres, is damaged. Moreover, defective fabrication of graphene free-standing metasurface may enhance the absorptive properties.

Ultra-broadband absorbance of nanometer-thin pyrolyzed-carbon film on silicon nitride membrane

“…Thin absorptive coatings are widely used in microwave and THz regions as polarizers, filters, attenuators, antennas and electromagnetic interference shielding layers [1][2][3][4][5][6][7][8][9]. Graphene and carbon-based thin films are very attractive in this respect because their electromagnetic response can be engineered by modifying synthesis conditions [10], doping [11], biasing [12], laser irradiation [13] and mechanical deformation [14].…”