Wavelength-decoupled geometric metasurfaces by arbitrary dispersion control

Conventional multicolor metaholograms suffer from the fundamental limitations of low resolution and irreducible noise because the unit structure functionality is still confined to a single wavelength. Here, we propose wavelength-decoupled metasurfaces that enables to control chromatic phase responses independently in a full range from 0 to 2 pi for each wavelength. The propagation phase associated with the geometric phase of rectangular dielectric nanostructures plays a critical role to embed a dual phase response into a single nanostructure. A multicolor metahologram is also demonstrated to verify the feasibility of our method that breaks through the fundamental constraints of conventional multicolor metaholograms. Our approach can be extended to achieve complete control of chromatic phase responses in the visible for general dual-wavelength diffractive optical elements.