Broadband high-efficiency multiple vortex beams generated by an interleaved geometric-phase multifunctional metasurface

Abstract

Vortex beams have witnessed tremendous development in the past decade by exhibiting profound implications for both fundamental physics and a multitude of novel engineering applications. In this work, broadband high-efficiency multiple vortex beams with independent topological modes and inclination angles are generated leveraging an interleaved geometric-phase multifunctional metasurface operating in a very broadband frequency range. A set of meta-atoms are elaborately engineered to offer broadband high-efficiency complete phase control covering the entire 2π range. Multiple geometric-phase sub-arrays implemented by the designed meta-atoms are synthesized into one metasurface via a shared-aperture interleaved manner, in which each sub-array can be individually manipulated and serves as an independent channel for launching a vortex beam. According to the established design methodology, two vortex beams with topological modes of −1 and +2 and distinct inclination angles are generated by one metasurface. Experimental results are provided to corroborate the proposed mechanism for multiple vortex beams generation, which exhibit broadband and high-efficiency features. The presented multifunctional metasurface paves the way for the generation of broadband high-efficiency multiple vortex beams in the microwave, millimeter-wave and terahertz regions. This work is of significance for high-capacity wireless communication applications, high-efficiency manipulation of electromagnetic waves, and novel design of radar and imaging systems.