A quasi-continuous all-dielectric metasurface for broadband and high-efficiency holographic images

Metasurfaces have an excellent ability to manipulate an incident electromagnetic wave through single-layer nano-structures, and thus, they have been successfully used to achieve the integration and miniaturization of optical devices. However, most reported metasurfaces achieve the phase/amplitude modulation through discrete antennas, which affect the performances of meta-devices. In this paper, a quasi-continuous metasurface composed of all-dielectric nanostrips with spatially continuous distribution is proposed. A meta-hologram based on quasi-continuous nanostrips is designed, and the broadband and high-efficiency properties of the designed sample are further demonstrated numerically. Compared to discrete structures, this demonstrated scheme can greatly increase the working bandwidth and energy efficiency of the meta-hologram. The quasi-continuous design can also be extended to some other applications that are associated with metasurfaces, such as meta-mirror, meta-lens, Bessel beam, orbital angular momentum generator and so on.