| Autor: |
Kim J; Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea., Jeon D; Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea., Seong J; Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea., Badloe T; Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea., Jeon N; Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea., Kim G; Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea., Kim J; Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea., Baek S; Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea., Lee JL; Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea., Rho J; Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.; Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.; POSCO-POSTECH-RIST Convergence Research Center for Flat Optics and Metaphotonics, Pohang 37673, Republic of Korea.; National Institute of Nanomaterials Technology (NINT), Pohang 37673, Republic of Korea. |
| Abstrakt: |
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. |
