Fig. 5
From: Dielectric metasurface zone plate for the generation of focusing vortex beams
The measured intensity profiles at the focal planes of the metasurface devices with topological charges of (a-d) l = +/− 2 and (f-i) l = +/− 3. The light wavelengths are (a, f) 633 nm, (b, g) 600 nm, (c, h) 570 nm, and (d, i) 532 nm, respectively. The images are shown in false-color. Scale bar:10 μm. e, j The calculated intensity profiles corresponding to that in (a, f)