High-order Poincaré beams generated by a dual-rings metasurface with orthogonal slit pairs

The generation and manipulation of high-order Poincaré (HOP) beams with metasurfaces have attracted wide attention and holds promise for applications in classical physics and quantum science. In this paper, we propose and experimentally demonstrate that a dual-rings metasurface composed of orthogonal slit pairs whose orientation varies with azimuth enables the generation of the HOP beams. The assumed novelty of this metasurface design lies in the combination of the geometric phase introduced by the rotation of slit pairs and the propagation phase introduced by the gap between two constituent slits of slit pairs, which realizes the elimination of co-polarized component and the superposition of cross-polarized component in the output fields. By controlling the orientation of the nano-slit pairs and adjusting the polarization states of incident light, the superposition of two orthogonal cross-polarized components with equal but opposite topological charges are realized, and correspondingly, the vector beam at an arbitrary point on the HOP sphere is generated. The principles and designs of metasurface are demonstrated by the finite-difference time domain simulation. The evolutions of satisfying quality HOP beams are investigated and experimentally verified. This work will be of significance for the applications of vector beams in different areas, such as precision metrology, optical micro-manipulation, and quantum information.