High-Efficiency Generation of Airy Beams with Huygens' Metasurface

Metasurfaces have shown great potential to generate Airy beams, but the available schemes with dielectric and plasmonic metasurfaces suffer from a lack of amplitude modulation and/or low transmission efficiency. Huygens' metasurfaces have the capability of manipulating electromagnetic wave fronts without reflection, and hence have offered a robust approach to exploit empowered functionalities, such as reflecting, refracting, and focusing plane waves. Here we propose a Huygens' metasurface structure comprised of a metal capacitor sandwiched between double-pair U-shaped ring resonators, which is capable of independently controlling the electric and magnetic dipole responses. The electric admittance and magnetic impedance can be tuned within a wide range, which enables us to achieve nearly arbitrary transmission amplitude and phase for the transmitted waves. The meta-atom of Huygens' metasurface can be designed to have ultrahigh transmission amplitude (nearly 100% for the maximum value), and the resultant Airy-beam generators assembled with the Huygens' metasurfaces present high transmission efficiency. We theoretically design transmissive Airy-beam generators that require polynary amplitude and binary phase distributions, and experimentally verify their excellent performances in terms of transmission efficiency. Our results, based on the independent control of electric admittance and magnetic impedance, can stimulate making high-efficiency wave-front manipulation devices with diversified functionalities in different frequency domains.