Diatomic Metasurface for Vectorial Holography

Abstract

The emerging metasurfaces with the exceptional capability of manipulating an arbitrary wavefront have revived the holography with unprecedented prospects. However, most of the reported metaholograms suffer from limited polarization controls for a restrained bandwidth in addition to their complicated meta-atom designs with spatially variant dimensions. Here, we demonstrate a new concept of vectorial holography based on diatomic metasurfaces consisting of metamolecules formed by two orthogonal meta-atoms. On the basis of a simply linear relationship between phase and polarization modulations with displacements and orientations of identical meta-atoms, active diffraction of multiple polarization states and reconstruction of holographic images are simultaneously achieved, which is robust against both incident angles and wavelengths. Leveraging this appealing feature, broadband vectorial holographic images with spatially varying polarization states and dual-way polarization switching functionalities have been demonstrated, suggesting a new route to achromatic diffractive elements, polarization optics, and ultrasecure anticounterfeiting.

Complete Control of Multichannel, Angle‐Multiplexed, and Arbitrary Spatially Varying Polarization Fields

“…Importantly, when the decomposition basis | e + 〉 is chosen as the circular basis | R 〉 = (1, 0) T or (| L 〉 = (0, 1) T ) and the incident beam has an arbitrary polarization state, from Equation , one can see that the resultant beam |Ψ ϑ 〉 = cos χ u + | R 〉 + e i ϑ sin χu − | L 〉 exactly describes the spin‐control functionality of the geometric metasurface with additional complex amplitude field control. This means that one can use coherent pixel polarization metaholography to generate arbitrary spatially varying polarization beams, including a full Poincaré beam and vectorial images . Additionally, for the noncircular case of | e + 〉 ≠ | R 〉 or | L 〉, such as in arbitrary spin to orbital conversion and a polarization‐multiplexed display, from Equation , one can see that the polarization pairs of |( e i ) ϑ 〉 or maintain orthogonality for a linearly polarized incident illumination.…”

“…The details of the orthogonality of the polarization pairs of |( e i ) ϑ 〉 or are given in Note S2 (Supporting Information). Here, the multichannel functionality is readily realized by coherent pixel polarization metaholography based on two pixel types with a fixed resolution, rather than by increasing the number of interleaved meta‐atoms or cells …”

“…Interestingly, the spin‐controllable character can be maintained when using the circular polarization basis. It should be noted that such an ultrathin multifunctional metasurface can be fabricated by standard complementary metal‐oxide semiconductor processes, and will enable a broad range of applications, such as optical polarization Möbius strips, polarization‐encrypted data, and quantum experiments, a fiber mode‐multiplexed communication system and arbitrary polarization‐multiplexed print images …”

“…Full Poincaré beams have been used to investigate physical systems with exotic nonlinear dynamics . The applications of optical images with spatially varying polarization manipulation include dynamic displays and information encryption . An attempt has also been made to reconstruct a Seifert surface structure by analyzing the polarization ellipse orientations of knotted polarization singularities …”

“…Recently, angle‐multiplexed metasurfaces consisting of reflective dielectric U‐shaped meta‐atoms were introduced to encode independent wavefronts at different incident angles. Diatomic metasurfaces consisting of two reflective orthogonal meta‐atoms were proposed for the polarization switching of vectorial holographic images. Continuously polarization‐controlled orbital angular momentum superpositions in multiple channels were reported using a single plasmonic metasurface .…”