Fig. 10
From: Planar metasurface-based concentrators for solar energy harvest: from theory to engineering
(a) Dispersion engineering of meta-lens: (I) Principal diagram of an achromatic meta-lens; (II) Schematic of a meta-lens element and SEM of a region of a fabricated meta-lens; (III) Measured normalized FL shifts (symbols) compared to simulations (lines) for meta-lens; (IV) Measured intensity distributions in the focal plane. (b) Schematic of a monochromatic meta-lens (left side of (I)) and a broadband achromatic meta-lens (right side of (I)). (II) Schematic of meta-unit archetypes. (III) Measured focusing efficiencies of the meta-lenses. (c) (I) Top view SEM images of achromatic meta-lens with four types of nanostructures. 2D (top panels of (II)) and 1D (bottom panels of (II)) intensity profiles of focal spots in focal planes. (III) Experimentally recorded focusing efficiency of the TiO2 meta-lens. (IV) Dependence of the focusing efficiencies on the polarization at 800 nm. (a, b) Reproduced with permission [152, 169]. Copyright 2018, NPG. (c) Reproduced with permission [203]. Copyright 2021, NPG