Circularly Polarized Transmissive Meta‐Holograms with High Fidelity

Abstract

Holography has attracted considerable interest because of its excellent capacity of recording and perfectly reconstructing the target information. The emergence of metasurfaces provides a new medium to code holograms in the subwavelength scale. Phase‐based holograms reported so far intrinsically decrease the image fidelity, because the amplitude information is ignored, especially for circularly polarized (CP) holograms. Herein, a novel strategy is proposed to achieve complex‐amplitude (CA) meta‐holography for CP transmissive waves with high fidelity and high polarization purity. Two cascaded patches are used to realize an amplitude modulation of 0–0.97 and a 2π phase shift in the microwave region. To verify and prove the concept, two CA meta‐holograms are designed, fabricated, and measured. The theoretical structural similarity index is 0.94 for the meta‐hologram reconstructing the letter “L” and 0.89 for the meta‐hologram reconstructing the Chinese character “”. It is experimentally demonstrated that the proposed CA method performs better, yielding higher‐accuracy reconstructed images than the phase‐only method. The polarization purity in the reconstructed images can be higher than 20 dB. The finding paves the way for synthesizing arbitrary wave‐front shapes and can find several applications in communication systems, imaging construction, and information processing.

Keywords

• circularly polarized waves
• complex-amplitude meta-holography
• high fidelity
• high polarization purity