Near-zero reflection of all-dielectric structural coloration enabling polarization-sensitive optical encryption with enhanced switchability

Nanophotonics

article

Chunghwan Jung¹  Junsuk Rho¹  Younghwan Yang²  Jaehyuck Jang¹  Trevon Badloe²  Taejun Lee²  Jungho Mun¹  Seong-Won Moon² 

[1] Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH);Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH);National Institute of Nanomaterials Technology (NINT)

关键词: anticounterfeiting;    cryptography;    dynamic metasurface;    full-color display;    structural color;    switchable metasurface;   

DOI  :  10.1515/nanoph-2020-0440

学科分类：社会科学、人文和艺术（综合）

来源: De Gruyter

【 摘 要 】

Structural coloration using metasurfaces has been steadily researched to overcome the limitations of conventional color printing using pigments by improving the resolution, lowering the toxicity, and increasing the durability. Many metasurfaces have been demonstrated for dynamic structural coloration to convert images at the visible spectrum. However, the previous works cannot reach near-zero scattering when colors are turned-off, preventing it from being cryptographic applications. Herein, we propose a completely on/off switchable structural coloration with polarization-sensitive metasurfaces, enabling full-colored images to be displayed and hidden through the control of the polarization of incident light. It is confirmed that the nanostructure exhibits the polarization-dependent magnetic field distributions, and near-zero scattering is realized when the polarization of incident light is perpendicular to the long axis of the nanofins. Also, the metasurfaces are made up of triple-nanofin structures whose lengths affect locations of resonance peaks, resulting in full-color spectrum coverages. With such advantages, a QR code image, a two-color object image, and an overlapped dual-portrait image are obtained with the metasurfaces. Such demonstrations will provide potential applications in the fields of high-security information encryption, security tag, multichannel imaging, and dynamic displays.

【 授权许可】

CC BY