Fig. 2. Metalens design and characterization.
(A) Schematic of the metalens that splits and focuses the two pairs of shearing circularly polarized light on the photosensor, where f is focal length, d' is the distance between the x and y shearing interference images, and ∆s' is the shearing distance. The inset shows the simulated and measured PSFs along the x and y direction, respectively. (B) Unit cell of the metalens is composed of rectangularly shaped silicon nanopillars on a sapphire substrate, with height H = 600 nm and period P = 350 nm. The rotation angle θ varies between 0 and π. The width Wx and length Wy vary between 100 and 250 nm. (C) Designed metalens phase profiles that can generate two pairs of shearing interference PSFs for LCP and RCP incident light, respectively. (D and E) Optical microscopy image (D) and scanning electron microscopy image (E) of the fabricated metalens.