Figure 39:

Dual-functional metasurface integrating color printing and hologram projection. (a) Schematic of the meta-device displaying both color printing and hologram projection. (b) Left panel: Schematic diagram of the Si nanodimer and nanofin structures on glass substrate. Right panel: phase responses and cross-polarized transmittances of these two meta-atoms at different orientation angles. (c) Design and experimental results of the dual-functional device. The clear bicolor pattern of the “earth map” results from the color printing mode, and the “red blossoms” and “green leaves” images result from the hologram projection mode. Modified with permission [350]. Copyright 2019, American Chemical Society. (d) Simulated cross-polarized spectra of the plasmonic shallow grating (PSG) units, which, respectively, display red, green, and blue colors. (e) Schematic diagram of the color adjusting system. The RGB color units and Ag nanomirror units are arranged into a 3 × 3 array in proper ratios to create colors with tunable chromaticity and brightness. (f) Left column: Results of the full-color printing, including the original image of two macaws (upper panel) and the optical image of a fabricated device (lower panel). Right column: SEM images of a fabricated sample (upper panel), and holographic images by means of blue, green, and red coherent illuminations. The pattern of the complete QR code (bottom right, lower panel) is restored from three measured subparts. Modified with permission [351]. Copyright 2020, Wiley-VCH.