Visible-light-band lateral dispersion multifocal metalens

Existing spectral separation methods often suffer from high costs and poor portability. We propose an RGB three-channel partitioned multi-focus metalens based on the geometric phase principle. The aperture is divided into three non-overlapping lateral zones integrating heterogeneous nanopillars with high spectral selectivity. These structures respond independently to right-handed circularly polarized light at 405, 513, and 633 nm, enabling precise phase modulation within each sub-aperture. Simulations demonstrate that the metalens focuses red, green, and blue light onto discrete lateral positions on a strictly co-planar focal plane, effectively circumventing the focal plane tilt inherent in traditional off-axis dispersion schemes. The achieved focusing efficiencies are 56.63%, 68.65%, and 76.55%, with focal spot sizes approaching the diffraction limit. Featuring an ultrathin profile and high integration, the proposed device provides a robust planar-optic solution for miniature color imaging and integrated multi-spectral systems.