Generating Microwave Bimerons with Propagation‐Variable Topologies by Single Metasurface

ABSTRACT Optical bimerons are 3D topological defects embedded within electromagnetic (EM) fields, which originate from pairing of two merons with opposite polarities and vortices, and are homeomorphic to optical skyrmions. They constitute a new family of structured light with nontrivial real‐space topology and exhibit great potential for higher‐capacity communication and even quantum information processing compared to skyrmions. However, most of current methods for generating bimerons generally are limited into optical regime and often require bulky optical paths, restricting their applications at lower frequencies like microwave or terahertz regimes. Here we propose a general method to generate bimerons at microwaves via a single metasurface that can module left‐ and right‐handed circular polarization independently—further reporting the first experimental realization of optical bimerons at lower frequencies. Furthermore, we theoretically and experimentally investigate how to control longitudinal topological texture of bimerons by encoding the Gouy phase and wavefront curvature phase into metasurfaces, demonstrating a new degree of freedom to (en)code information by the bimeronic beams. Our work paves the way for future applications of bimeronic beams at lower frequencies like topologically enhanced information encoding and microwave communication, to name a few.