Broadband high-efficiency meta-holography from all-dielectric quasi-continuous metasurfaces

The compactness and particular optical design make metasurface a competitive candidate for holographic display and storage. Recently, the selection and optimization for the used metasurface structures and types have become research spots. Now the most researched and demonstrated meta-holograms are often based on discrete structures, which can achieve high efficiency but comparatively narrow working bandwidths or a wide wavelength range but low power efficiency. Therefore, contemporary meta-holograms struggle for realizing simultaneous broadband and high efficiency. In this paper, all-dielectric quasi-continuous metasurfaces composed of nanostrips are introduced to expand the operating bandwidth for high efficiency meta-holography. Benefiting from the associated Pancharatnam–Berry phase, the nanostrips with spatially orientation angles continuous changes can realize arbitrary phase modulation. For the first time, the average power efficiency of a meta-hologram is experimentally measured to be 56.63% over a broad wavelength band ranging from 500 to 1000 nm. In addition, based on this kind of all-dielectric quasi-continuous nanostrips, we also design and experimentally achieve multicolor three-dimensional (3D) holographic images. Actually, such all-dielectric quasi-continuous methodology proposed here can be used to design other functional meta-devices, including optical metalens, nanoprinting, and information encryption.