Figure 4
(a) Schematic of the nanostructures in focusing layer. The TiO2 nanopillar is placed on a glass substrate. (b,c) Phase compensation and efficiency with the change of diameter of cylindroid nanopillars at the wavelengths of 470 nm, 530 nm and 630 nm, respectively. (d,e) Phase compensation and efficiency with the change of outer diameter and the inner diameter of 50 nm of annular nanopillars at the wavelengths of 470 nm, 530 nm and 630 nm, respectively.
