Independent control of polarization and phase by spin-decoupled Archimedes’ spiral metasurface

Abstract Polarization and phase are two fundamental properties of electromagnetic waves, and their precise control is crucial for the tailored manipulation of electromagnetic wavefronts. Recently, complex vector beams have attracted increasing attention in the field of metamaterials. Nevertheless, achieving independent control of polarization and phase remains a significant challenge. In this work, we propose a completely spin-decoupled Archimedes’ spiral metasurface, in which the engineered surface current path enable the generation of spin-decoupled geometric phases. The polarization and phase information is represented using two orthogonal circular polarization components, which can be simultaneously and independently controlled by tailoring the starting point of the metallic spiral and its entire rotate angle. In this manner, we designed a bifunctional metasurface capable of achieving beam focusing and vortex beam generation for circularly polarized waves. For linearly polarized waves, other metasurfaces were developed to realize vortex beam with uniform cross-polarization and vector vortex beam generation, respectively. Subsequently, these prototypes were fabricated and experimentally characterized. Both the simulation and experimental results confirm that the proposed designs not only possess the capability to impart spin-decoupled geometric phase for circularly polarized waves, but also enable independent control over phase and polarization for linearly polarized waves. This work expands the function of spin-decoupled metasurfaces and offers a novel strategy for the generation of complex vector beams.