Dual-Band Operating Metaholograms with Heterogeneous Meta-Atoms in the Visible and Near-Infrared

Metasurfaces consisting of sub-wavelength structures have been researched as an alternative ultra-thin platform for flat optical devices. One promising application is in multifunctional metaholograms for anticounterfeit purposes. By extending the operating wavelength band of conventional meta-holographic optics, which typically operate only in the visible, it is possible to realize a security-enhanced anticounterfeit technology. Here, a dual-band reflective metahologram that operates simultaneously in the visible and near-infrared domains using heterogeneous meta-atoms, is proposed. The device consists of both hydrogenated amorphous silicon and gold metasurfaces in the same plane, where the two materials exhibit maximized conversion efficiency at wavelengths of 532 and 980 nm, respectively. The demonstrated wavelength-multiplexed metahologram can provide a pragmatic path toward a security-enhanced anticounterfeit technology.