Kim Joohoon, Jeon Dongmin, Seong Junhwa, Badloe Trevon, Jeon Nara, Kim Gyeongtae, Kim Jaekyung, Baek Sangwon, Lee Jong-Lam, Rho Junsuk
Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.
Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.
ACS Nano. 2022 Mar 22;16(3):3546-3553. doi: 10.1021/acsnano.1c10100. Epub 2022 Feb 19.
Metasurface-driven optical encryption devices have attracted much attention. Here, we propose a dual-band vectorial metahologram in the visible and ultraviolet (UV) regimes for optical encryption. Nine polarization-encoded vectorial holograms are observed under UV laser illumination, while another independent hologram appears under visible laser illumination. The proposed engineered silicon nitride, which is transparent in UV, is employed to demonstrate the UV hologram. Nine holographic images for different polarization states are encoded using a pixelated metasurface. The dual-band metahologram is experimentally implemented by stacking the individual metasurfaces that operate in the UV and visible. The visible hologram can be decrypted to provide the first key, a polarization state, which is used to decode the password hidden in the UV vectorial hologram through the use of an analyzer. Considering the property of UV to be invisible to the naked eye, the multiple polarization channels of the vectorial hologram, and the dual-band decoupling, the demonstrated dual-band vectorial hologram device could be applied in various high-security and anticounterfeiting applications.
超表面驱动的光学加密设备备受关注。在此，我们提出一种用于光学加密的可见和紫外（UV）波段的双波段矢量超全息图。在紫外激光照射下可观察到九个偏振编码的矢量全息图，而在可见激光照射下会出现另一个独立的全息图。所提出的在紫外透明的工程氮化硅用于展示紫外全息图。使用像素化超表面对不同偏振态的九个全息图像进行编码。通过堆叠在紫外和可见光波段工作的单个超表面，实验实现了双波段超全息图。可见全息图解密后可提供第一个密钥，即偏振态，该偏振态用于通过使用分析仪解码隐藏在紫外矢量全息图中的密码。考虑到紫外线肉眼不可见的特性、矢量全息图的多个偏振通道以及双波段解耦，所展示的双波段矢量全息图设备可应用于各种高安全性和防伪应用中。
