Longitudinal Multifoci Metalens for Circularly Polarized Light

The focusing performance of a 40 nm-thick metasurface lens is experimentally demonstrated. The longitudinal multifoci flat metasurface lens is illuminated with a linearly polarized light (|LP>) beam at normal incidence. Three focal planes with circular polarization states (|L> and |R>) are observed. The theoretical intensity profile of the light behind the metalens in the y–z plane agrees well with theoretical predictions.