Fig. 3

Inverse design of metalenses. a Comparison between (left) unit cell-based design and (right) inverse design. b Normalized intensity profile on longitudinal plane of inverse-designed high-NA achromatic metalens. Dotted lines indicate focal plane of metalens. (a) and (b) are reproduced with permission [110] (Copyright 2020, Optical Society of America). c Surrogate-model-based fast approximate solving of forward simulation. d Photograph of fabricated metalens with a diameter of 1 cm and achromatic and polarization-insensitive functionalities. (inset) SEM image of metalens (scale bar = 500 nm). e Experimental intensity distribution on xz-plane for wavelengths of (top) 488 nm, (middle) 532 nm, and (bottom) 658 nm. c-e are reproduced with permission [92] (Copyright 2022, Springer Nature). (f) Schematic of coupled-mode theory (CMT)-based forward simulation model. g Comparison of computation time between (red) single finite-element method simulations and (black) one iteration using CMT approach. f and g are reproduced with permission [111] (Copyright 2021, American Chemical Society)