Fig. 1. Illustrations of multiwavelength holograms, multiwavelength waveplates, and 3D holograms using bilayer metasurfaces.

a Illustration of a multiwavelength hologram. The metasurface is designed to achieve independent phase modulation at two wavelengths. b Illustration of a multiwavelength waveplate using a combination of two polarization-sensitive rectangular nanopillar geometries. The bilayer metasurface functions as a half-wave plate and a quarter-wave plate at two different, and independent, wavelengths. c Schematic of a metaoptic for producing a 3D hologram with on-axis evolution. The bilayer metasurface comprises nanodisks and nanoposts to enable polarization-insensitive control over both amplitude and phase