Photonic Encryption Platform <i>via</i> Dual-Band Vectorial Metaholograms in the Ultraviolet and Visible

TLDR

Metasurface-driven optical encryption devices have attracted much attention. We propose a dual-band vectorial metahologram operating in the visible and ultraviolet regimes for optical encryption. The device uses stacked silicon nitride metasurfaces that operate in UV and visible, where the visible hologram decrypts a polarization key that unlocks the UV hologram via an analyzer. The device displays nine polarization‑encoded holograms in UV and visible, demonstrating dual‑band decoupling and suitability for high‑security and anticounterfeiting applications.

Abstract

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.