Fig. 6
From: Planar metasurface-based concentrators for solar energy harvest: from theory to engineering
(a) (I) Schematic of the c-Si meta-lens. (II) Meta-lens consists of c-Si nanobricks on a sapphire substrate. Focusing performance of the meta-lens in air (III) and immersion oil (VI). (b) (I) Schematic of a meta-lens operating in transmission mode (left panel). Right panel: Side view and top view of the meta-lens building block. Top view SEM image of the center portion (left side of (II)) and a portion at higher magnification (right-top of (II)) of the fabricated meta-lens. Side view SEM image of the edge of the meta-lens (right-bottom of (II)). (III) Solid lines: required analog phase. Circles: digitized phase profiles of the meta-lenses designed at wavelengths of 660 nm (left), 532 nm (middle), and 405 nm (right). Corresponding 2D simulated intensity profiles at focal planes. (a) Reproduced with permission [160]. Copyright 2018, American Chemical Society (ACS). (b) Reproduced with permission [119]. Copyright 2016, ACS