Fig. 7: Images of fabricated metalenses and fabrication methods via the DLW technique.

a Photograph of the fabricated metalens, scale bar: 4 mm. b SEM image indicates the microscopic laser-written spatially varying nanogrooves, scale bar: 300 nm. c Photograph of the fabricated metasurfaces (left), scale bar: 5 mm. Optical image of the metasurface created using a polariscope (right), scale bar: 25 μm. The orientation of structures in one period is represented by the red bars. Inset: the induced nanostructures are depicted in the SEM image, scale bar: 500 nm. d Dark-field image depicting the cross-sectional view of the fabricated metadevice, scale bar: 50 μm. Inset: photograph of the fabricated metadevice. e SEM image shows the arrangement of nanopores, with a magnify image reveals the detail. f SEM image of the entire fabricated metalens (left). SEM image shows the concentric graphene oxide nanogrooves (right). g Schematic of the light modulation process employed by PPLL, which generates patterned pulses with energy distribution characterized by gradient boundaries. The polarization direction is indicated by the arrows. h Schematic of fabrication of nanohole arrays with optimized non-diffracting laser lithography, scale bar: 500 nm. i Schematic of optimization in phase diagram by a reverse-axicon phase diagram. j SEM images of fabricated metalens consists of 3-mm-diameter nanoholes with different depths. a, b Reprinted with permission from ref. ¹⁵¹. Copyright 2018 American Chemical Society. c Reprinted with permission from ref. ¹⁵². Copyright 2019 National Academy of Sciences. d, e Reprinted with permission from ref. ¹⁵³. Copyright 2024 John Wiley and Sons. f Reprinted with permission from ref. ¹⁵⁴. Copyright 2021 American Chemical Society. g Reprinted with permission from ref. ¹⁵⁶. Copyright 2022 Springer Nature. h–j Reprinted with permission from ref. ¹⁵⁷. Copyright 2025 John Wiley and Sons