Arxiv – Darker than black: radiation-absorbing metamaterial
We show that corrugated surfaces of hyperbolic metamaterials scatter light preferentially inside the media, resulting in a very low reflectance and ultimate dark appearance in the spectral range of hyperbolic dispersion. This phenomenon of fundamental importance, demonstrated experimentally in arrays of silver nanowires grown in alumina membranes, originates from a broad-band singularity in the density of photonic states. It paves the road to a variety of applications ranging from the stealth technology to high-efficiency solar cells and photodetectors
DRAMATIC REDUCTION OF REFLECTANCE OFF CORRUGATED HYPERBOLIC METAMATERIAL. Panel (a): the phase space “volume” enclosed by two different surfaces of constant frequency, in the cases when components of the dielectric permittivity tensor are all positive (left) and have opposite signs (right). Panel (b): angular reflectance profiles measured on untreated (circles) and roughened (diamonds) parts of the same membrane sample in spolarization and p-polarization. Inset: reflectance profiles in the corrugated sample (same as in main panel (b), zoomed). Panels (c) and (d): topography profiles of the untreated (c) and corrugated (d) samples.
We thus have demonstrated that the reflectance of a hyperbolic metamaterial is significantly reduced upon corrugation of its surface, in an agreement with the theoretical prediction. With the original concept equally applicable to all parts of the electromagnetic spectrum, our result thus opens an entirely new route towards radiation-absorbing materials and surfaces, with wide range of applications spanning from solar light harvesting to radar stealth technology.