Near-zero reflection of all-dielectric structural coloration enabling polarization-sensitive optical encryption with enhanced switchability
Near-zero reflection of all-dielectric structural coloration enabling polarization-sensitive optical encryption with enhanced switchability
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DOI：
10.1515/nanoph-2020-0440
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发表时间：
2021-12-11
期刊：
影响因子：
7.5
通讯作者：
Rho, Junsuk
中科院分区：
文献类型：
--
作者：
Jung, Chunghwan;Yang, Younghwan;Rho, Junsuk
通过提高分辨率、降低毒性和增加耐用性，人们不断研究利用超表面进行结构着色，以克服使用颜料进行传统彩色打印的局限性。许多变形表面已经被演示用于动态结构着色以转换可见光光谱处的图像。然而，以前的工作无法在关闭颜色时达到接近零的散射，从而阻止了它的密码应用。在这里，我们提出了一种完全可开/关的偏振敏感亚表面结构着色，通过控制入射光的偏振来实现全色图像的显示和隐藏。证实了该纳米结构具有偏振相关的磁场分布，当入射光的偏振方向垂直于纳米鳍片的长轴时，实现了近零散射。此外，超表面由三个纳米翅片结构组成，其长度会影响共振峰的位置，从而产生全彩色光谱覆盖。利用这样的优点，利用元表面获得二维码图像、双色对象图像和重叠的双人像图像。这样的演示将在高安全性信息加密、安全标签、多通道成像和动态显示领域提供潜在的应用。
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.