Optical Magnetism-Induced Dual Anisotropy in Dielectric Nanoantennas

摘要

Directional polarization of atoms in crystalline dielectrics leads to anisotropicpermittivities that usually enable phase delay between two orthogonal componentsof light in waveplates. However, amplitude-type anisotropy is seldomobserved in natural dielectrics because optical absorption of transparentmaterials is mainly dominated by polarization-insensitive bandgap. This workintroduces the co-existence of both amplitude- and phase-type anisotropiesin artificial dielectric rectangle nanoantennas by using a united approachof directionally excited magnetic resonances. When anti-parallel magneticdipolar modes (AMDMs) are induced horizontally, the resulting electric fieldsat the antenna?substrate interface behave, surprisingly, like those of surfaceplasmonic polaritons (SPPs), leading to nearly full reflectance of light. But, forthe incidence of the other polarization, only vertically located AMDMs arisewith high transmission, thus yielding amplitude-type anisotropy. For phasetypeanisotropy, both orthogonal polarizations of light excite vertical AMDMswith high transmission and an additional polarization-dependent phase. Bothanisotropies are multiplexed into a polarization-dependent color-printed hologramfor optical anticounterfeiting.