Multichannel Metasurfaces for Anticounterfeiting

Anticounterfeiting is an effective method to decrease the harmful effects of counterfeit goods. Optical metasurfaces can tailor light's amplitude, phase, and polarization at subwavelength resolution, enabling compact optical devices with unusual functionalities that can outperform conventional bulky components. We propose and experimentally demonstrate a multichannel metasurface device that can reconstruct helicity multiplexed holographic images and hide a grayscale image in the polarization profile of a light beam, which can be used for high-level anticounterfeiting. A dielectric metasurface consisting of nanopillars with spatially variant orientations is used to realize distinct functionalities in multiple channels. The two holographic images can be switched by changing the helicity of the incident light, while the encoded image in the polarization profile of the light beam can be revealed by a polarizer. Our work demonstrates the feasibility of the multifunctional device based on the independent control of phase and polarization in different channels, which may open an alternative window for compact optical devices with high density of functionalities for anticounterfeiting.