Abstract

By allowing almost arbitrary distributions of amplitude and phase of electromagnetic waves to be generated by a layer of sub-wavelength-size unit cells, metasurfaces have given rise to the field of meta-holography. However, holography with circularly polarized waves remains complicated as the achiral building blocks of existing meta-holograms inevitably contribute to holographic images generated by both left-handed and right-handed waves. Here we demonstrate how planar chirality enables the fully independent realization of high-efficiency meta-holograms for one circular polarization or the other. Such circular-polarization-selective meta-holograms are based on chiral building blocks that reflect either left-handed or right-handed circularly polarized waves with an orientation-dependent phase. Using terahertz waves, we experimentally demonstrate that this allows the straightforward design of reflective phase meta-holograms, where the use of alternating structures of opposite handedness yields independent holographic images for circularly polarized waves of opposite handedness with negligible polarization cross-talk.

Highlights

  • Holography, a three-dimensional (3D) imaging technique, was originally proposed by Gabor[1]

  • By alternating chiral resonators that only contribute to holographic images for either left-handed or right-handed waves, we demonstrate a straightforward method for multiplexing reflective holograms for circularly polarized waves

  • We use two types of 2D-chiral double-split ring resonators (DSRRs) that are backed by a mirror as the unit cells of our meta-hologram to achieve circular-polarizationselective reflection with a high efficiency, see Fig. 2a and Methods section

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Summary

Introduction

Holography, a three-dimensional (3D) imaging technique, was originally proposed by Gabor[1]. Initial holograms recorded interference fringes of an object beam and a reference beam to store both the phase and amplitude information of the object. When such a hologram is illuminated by the same reference beam, a 3D image of the object will be reconstructed at the object’s original position. By alternating chiral resonators that only contribute to holographic images for either left-handed or right-handed waves, we demonstrate a straightforward method for multiplexing reflective holograms for circularly polarized waves. We experimentally show that the resulting meta-hologram generates independent holographic images for reflected terahertz waves of opposite handedness. In contrast to conventional reflectors, the planar chiral meta-hologram does not change the handedness of circularly polarized waves upon reflection (Fig. 1)

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