A Reconfigurable Active Huygens' Metalens

Abstract

Metasurfaces enable a new paradigm to control electromagnetic waves by manipulating subwavelength artificial structures within just a fraction of wavelength. Despite the rapid growth, simultaneously achieving low‐dimensionality, high transmission efficiency, real‐time continuous reconfigurability, and a wide variety of reprogrammable functions is still very challenging, forcing researchers to realize just one or few of the aforementioned features in one design. This study reports a subwavelength reconfigurable Huygens' metasurface realized by loading it with controllable active elements. The proposed design provides a unified solution to the aforementioned challenges of real‐time local reconfigurability of efficient Huygens' metasurfaces. As one exemplary demonstration, a reconfigurable metalens at the microwave frequencies is experimentally realized, which, to the best of the knowledge, demonstrates for the first time that multiple and complex focal spots can be controlled simultaneously at distinct spatial positions and reprogrammable in any desired fashion, with fast response time and high efficiency. The presented active Huygens' metalens may offer unprecedented potentials for real‐time, fast, and sophisticated electromagnetic wave manipulation such as dynamic holography, focusing, beam shaping/steering, imaging, and active emission control.

Active Anisotropic Coding Metasurface with Independent Real‐Time Reconfigurability for Dual Polarized Waves

“…Actually, the active anisotropic coding metasurface can also be used to control the near-filed behaviors, which has promising perspectives in applications of compact lens, [34] near-field communication, [43] etc. Actually, the active anisotropic coding metasurface can also be used to control the near-filed behaviors, which has promising perspectives in applications of compact lens, [34] near-field communication, [43] etc.…”

“…To solve the problem of fixed wave-manipulations by passive metasurfaces, more efforts have been devoted to realize active control of EM behaviors of metasurfaces upon the external stimulations by incorporating with tunable materials or components, [30,31] such as diodes, [32][33][34][35] graphene, [36,37] phase-change materials, [38,39] etc. Recently, coding metasurfaces have been proposed to control the wave functionalities using unique particles with, for example, either the "0" or "1" state in 1-bit coding case.…”

“…linearly polarized excitation, [32][33][34][35][36][37][38] leaving much potentials unexploited. Undoubtedly, the active anisotropic metasurfaces for independent dual-polarized manipulations of EM waves will further increase their information capabilities, bringing new degrees of freedom in achieving versatile tunable functionalities that are highly desirable from application aspects.…”

Design of 1-Bit Digital Reconfigurable Reflective Metasurface for Beam-Scanning

“…As a result, it has more potential applications since it can work in a wider bandwidth [9][10][11]. These electronically-controlled digital reflective metasurfaces have been proposed for different practical applications such as tunable absorbers, reconfigurable antennas, EM wave modulators, tunable chiral metamaterials, reprogrammable hologram, and so on [12,13].…”

Multifunctional Metasurfaces Based on the “Merging” Concept and Anisotropic Single-Structure Meta-Atoms

“…People utilized the concept of Huygens' surface to construct transmission-mode metasurfaces with high efficiencies, but such devices usually require complex 3D non-flat meta-atoms with both electric and magnetic resonators incorporated [24,26]. Due to the complexities in meta-atom design, multifunctional meta-devices realized based on such a scheme are rarely seen, except a transmissive functionality-tunable device recently realized with controllable active elements incorporated [96].…”