Spatial multiplexing plasmonic metalenses based on nanometer cross holes

Metasurfaces enable a spatially varying optical response to mold optical wavefronts into shapes that can be designed at will. Recurring to the excellent metasurfaces, spatial multiplexing metalens with multiple focal spots distributing along the transverse or longitudinal direction and vortex metalens with controllable topological charge are performed. These metalenses are composed of identical cross holes etched on the silver film and each cross hole can be taken as an equivalent half wave plate. The proposed spatial multiplexing metalenses can focus the light beam and spin the wave front, and their advantages of multifunction, high signal-to-noise ratio and ease to manipulate are favorable for expanding the application of plasmonic metalenses in optical manipulation. (paper)