Fig. 10

a A schematic diagram which helps the understanding of the generalized Snell’s law of refraction. Refraction angle is affected by an additional phase discontinuity term. [144] b SEM image of nanoantenna array fabricated on a silicon wafer. The unit cell represented as a yellow color is periodically arranged with a periodicity of Γ. Each V-shaped antennas have 220 nm width and 50 nm thickness [144]. c Top: schematic of a flat lens. Bottom: phase distribution on the flat lens. Hyperboloidal radial phase distribution makes an incident plane wave focus on a point F [145]