Arbitrary manipulations of focused higher-order Poincare beams by a Fresnel zone metasurface with alternate binary geometric and propagation phases

The manipulation of high-quality vector beams (VBs) with metasurfaces is an important topic and has potential for classical and quantum applications. In this paper, we propose a Fresnel zone (FZ) metasurface with metallic nanoslits arranged on FZs, which sets alternate binary geometric and propagation phases to cancel the incident spin component and focus the converted spin component (CSC). The rotation designs of nanoslits transform the incident polarization state on the conventional Poincare sphere to VBs on the higher-order Poincare (HOP) sphere. The two orbital angular momentum states of the CSCs were manipulated, and the focused HOP beams were generated. The experimental results demonstrate the broadband generation of arbitrarily focused HOP beams of high quality under the illumination of the red (632.8 nm), green (532 nm), and blue (473 nm) light. This work will be of significance for the applications of VBs in different areas, such as precision metrology, optical micromanipulation, and quantum information. (C) 2022 Chinese Laser Press