Fig. 1
From: Wavelength-decoupled geometric metasurfaces by arbitrary dispersion control
Operation schematic of the wavelength-decoupled metasurface. a By illumination of green (λ = 532 nm) and red (λ = 635 nm) light, multicolor holographic images can be generated from the metasurface. It features a dual phase response embedded in a single nanostructure that enables independent phase control for two wavelengths. b Illustration of the design principle. The lower white line represents an arbitrary cross-polarization propagation phase curve of a certain dielectric nanorod while φ1 and φ2 indicate specific values at wavelengths of λ1 and λ2, respectively. A phase pair of this state can be represented as (φ1, φ2). If this nanorod rotates by the angle α, the phase curve moves parallel by 2α. Therefore, the phase pair becomes (φ1 + 2α, φ2 + 2α); hence, any phase pairs in which phase difference equals to (φ1 − φ2) can be represented by one nanorod with appropriate rotation angles. Dashed lines are to guide the eye
