Abstract
Vectorial holography has gained a lot of attention due to the promise of versatile polarization control of structured light for enhanced optical security and multi-channel optical communication. Here, we propose a bifunctional metasurface which combines both structural color printing and vectorial holography with eight polarization channels towards advanced encryption applications. The structural colour prints are observed under white light while the polarization encoded holograms are reconstructed under laser illumination. To encode multiple holographic images for different polarization states, a pixelated metasurface is adopted. As a proof-of-concept, we devise an electrically tunable optical security platform incorporated with liquid crystals. The optical security platform is doubly encrypted: an image under white light is decrypted to provide the first key and the corresponding information is used to fully unlock the encrypted information via projected vectorial holographic images. Such an electrically tunable optical security platform may enable smart labels for security and anticounterfeiting applications.
Highlights
Vectorial holography has gained a lot of attention due to the promise of versatile polarization control of structured light for enhanced optical security and multi-channel optical communication
The characteristics of light have been utilized in diverse fields frequently seen in everyday life for example, full color displays have been realized through spectral engineering, holographic displays through outgoing light phase modulation, advanced microscopy technologies through polarization control, and optical fiber communications transmitting orbital angular momentum (OAM) states have all been used to take advantage of the many degrees of freedoms of light to convey a variety of information
We have numerically and experimentally demonstrated vectorial holographic color prints which have the multifunctionality of structural color prints and LCassisted dynamic vectorial holographic image projection
Summary
Design principle for the independent modulation of the phase and amplitude of light. Metasurfaces consist of arrays of Voltage. In the high-frequency regime, most multipoles have comparable amplitudes so that complex far-field interactions are expected No responses such as directional scattering are observed due to the losses in the Si (Supplementary Note 1 and Supplementary Fig. 1). The full azimuth angle 2ψ can be achieved by modulating the phase difference 2δ between RCP and LCP from 0 to 2π, resulting in every linear polarization state on the S1-S2 plane. 4φ, the phase of the outgoing RCP and LCP is modulated by the absolute angle of the meta-atom: φ and Àφ þ δ as shown in. The effect of the twin-image on the total diffraction efficiency is numerically analyzed and experimentally characterized in Supplementary Note 6 and
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