Design and demonstration of a wide-angle and high-efficient planar metasurface lens

In this paper, a gradient index metasurface lens (metalens) for planar wide-angle and high-efficient focusing is designed, fabricated and tested. By properly designing the ultra-thin double-layer metasurfaces with gradient meta-atoms, the proposed metalens can focus wide-angle incident wave efficiently working at transmission regime. The numerical and experimental results demonstrate that the metalens can focus oblique incident wave continuously up to 40 degrees within half maximum focused field intensity of normal one on one side. Besides, the accurate focused spot mapping dependent on both the normal and oblique incident angle is established and analyzed quantitatively. The designed metalens demonstrate good achromatic capability with large spatial incident angle view. This work of wide-angle and high-efficient metalens enhances the performance of conventional ones which operate within narrow incident angle range and can opens up new ways to develop some novel ultra-thin devices like wide-angle scanning antenna and planar retro-reflector in microwave band.