Figure 1.

(a) The three-dimensional schematic of TiO₂ antenna arrays with equivalent separation formed on a silica substrate. A plane wave is incident to the antenna array from the silica substrate, and the focus length is f. The focus is a narrow line in the y-direction; (b) Schematic of the unit cell of the metalens: the circular TiO₂ post with a height of 488 nm on a 200-nm-thick silica substrate. The size (W) of the unit cell is 318 nm × 318 nm; (c) Schematic of the metalens from the view of the negative direction of the z-axis; (d–f) The schematic for recording the transmission, reflection and absorption coefficient of every nanopillar; (g–i) The according result of transmission, reflection and absorption coefficient map for different nanopillars with the radii ranging from 10–150 nm in the entire visible spectrum.