ZrN fractal-graphene-based metamaterial absorber in the visible and near-IR regimes

The absorption characteristics of zirconium nitride (ZrN)-based metamaterial absorber of fractal geometry are studied. The proposed absorber is comprised of fractal metasurface at the top having subwavelength-sized periodic pattern of specially designed ZrN circular nano-discs arranged over silicon dioxide (SiO2) substrate. A tri-layer graphene, owing to its exhibiting better tunability, is introduced at the interface of metasurface and substrate. The bottom side of SiO2 is coated with silver nanolayer to block transmission. The absorptivity essentially depends on the kind of fractal design used in metasurface to configure the absorber. The obtained results exhibit the absorption characteristics to remain insensitive to the incidence polarizations. The chemical potential of graphene could be used to tune the spectral characteristics. Such a kind of absorber would be useful for filtering, antireflection coating, and solar energy harvesting applications in the visible and near-infrared regimes of electromagnetic spectrum.