Ultra-broadband metasurface holography via quasi-continuous nano-slits

Metasurface holography has attracted growing interest in the optical fields, owing to its potentiality in various applications such as the high-capacity data storage and three-dimensional imaging with large viewing angle. However, most reported metasurface holograms consist of discrete meta-atoms, which limit the broadband performances of the holographic devices. In this paper, a metasurface hologram, composed of quasi-continuous nano-slits, is demonstrated to realize high-efficiency and broadband holographic images with both simulation and experiment. The quasi-continuous metasurface hologram proposed here can effectively expand the working bandwidth, especially when the characteristic dimension of the meta-hologram is at deep-subwavelength scale. We anticipate that the proposed approach could greatly promote the applications of metasurface, such as flat lens, vortex beam generator and optical storage.