Fig. 7

(a) Topological optimizations for a 75° deflection meta-grating. Left: a plot of absolute efficiency of a meta-grating (see interior graphs at different stages) over 350 iterations. The sharp dips are induced by the applied geometric modifications in order to remove the teeny features that are too difficult to fabricate. Middle: a scanning electron microscope (SEM) image of meta-grating operated at 1050 nm. Right: the measured efficiencies. (b) An illustration of GAN (formed with a generator and a discriminator) for meta-grating generation. The well-trained generator produces grating images at the desired angle and wavelength, while the discriminator helps to instruct the generator to create high-performance devices. (c) A fused framework (see the diagram) of a compositional pattern-producing network and a cooperative coevolution algorithm for metaatom-based deflective gratings. The bottom panel showcases the SEM image of a manufactured eight atoms (alighted in the top frame) with simulated E _y field profile (right). (d) A liquid crystal (LC) based tunable meta-grating for high switching efficiencies and wide angular deflection (±72°). Top: the inverse design and global optimization area. Bottom: the diffraction efficiencies of an optimized triple-grating. The data expresses -1 order diffraction efficiency of 62% (red line) for voltage-on state and +1 order efficiency of 76% (teal line) in the voltage-off status. Figures reproduced with permission: (a) Ref. [86], Copyright 2017 ACS; (b) Ref. [87], Copyright 2019 ACS; (c) Ref. [88], Copyright 2020 Wiely;(d) Ref. [89], Copyright 2020 ACS