A Vortex-focused Beam Metalens Array in the Visible Light Range Based on Computer-generated Holography

Abstract In recent years, metasurfaces have demonstrated a tremendous development potential and applicability in various fields as they have overcome the problems associated with traditional optical devices, including bulkiness and difficulties related to integration. The vortex beam can carry an unlimited amount of orbital angular momentum which can greatly increase the capacity of the communication system and thus attain a tremendous applicability potential in communication and information transmission. In this study, a vortex-focused beam metalens array is designed based on computer-generated holography technology for use in the visible light range. The antenna’s unit structure is arranged according to the phase distribution designed using computer-generated holography technology. The metalens array can convert circularly polarized light into a vortex beam and can focus the vortex beam. At the wavelengths of 420 nm, 550 nm, and 660 nm, the average conversion efficiency exceeds 80%, and the phase distribution is in the range of 0-2π. The metalens array can simultaneously generate and focus the vortex beams. We also studied the focusing effect of different vortex beams, and we analyzed and compared the focal length and full width at half maximum of metalens at different wavelengths and different topological charges. In addition, the focusing of the primary color light by the 3 × 3 metalens array is simulated. The design presented in this study is envisaged to be applied extensively in the fields of optical photography and optical communication systems.