All-Dielectric Meta-Atoms for Three-Dimensional Isotropic Chiral Metamaterials

Abstract

We consider an all-dielectric chiral meta-atom, fabricable by a lithographic and liftoff technique, such that a random arrangement of these meta-atoms creates a scalable, isotropic, and nonabsorbing three-dimensional (bulk) chiral medium in the near-infrared. The meta-atom is made of silicon and consists of a cube with a gammadion on top. We show that the presence of either an electric or magnetic dipole resonance in the cube leads to substantial enhancement of the optical chirality. We also show that in both metasurfaces and three-dimensional metamaterials made of such meta-atoms, the optical chirality can persist despite the random orientation of these meta-atoms. Our results point to a route toward creating strong chiral responses in self-assembled metamaterials.