Broadband Polarization‐Switchable Multi‐Focal Noninterleaved Metalenses in the Visible

Multi‐focal lenses are widely applied in zoom imaging, parallel laser processing, 3D displays, among others. However, conventional refractive or diffractive elements cannot realize independently switchable multi‐focal points at arbitrary spatial positions. The ultra‐thin metasurface provides a compact solution while the commonly used interleaved meta‐units scheme deteriorates the performance of the meta‐devices. Here the authors propose all‐dielectric noninterleaved metalenses with polarization‐switchable multi‐focal points. By fully using the degrees of freedom of the single rectangular nanopillar, up to three independently switchable focal points at any spatial position can be realized in a metalens with a single‐structure lattice. With the near‐zero crosstalk between orthogonal polarization channels, polarization detection, zoom imaging, variable‐parameter phase detection, and parallel laser lithography are demonstrated. The multichannel scheme by fully utilizing the polarization freedom paves the way for various multifunctional components. Polarization‐switchable multi‐focal noninterleaved metalenses (PMNM) composed of TiO2 rectangular nanopillars are proposed in the visible region. By using the different degrees of freedom of the Jones matrix, up to three sets of independent phases can be encoded into a single meta‐unit. Bi‐focal polarization detection, multi‐level zoom imaging, variable‐parameter phase detection, and parallel laser lithography have been experimentally demonstrated.