A Reconfigurable Active Huygens' Metalens

TL;DR

This paper introduces a reconfigurable active Huygens' metasurface that enables real-time, multi-functional electromagnetic wave control, demonstrated by a microwave metalens capable of dynamic, multi-spot focusing with high efficiency.

Contribution

It presents the first reconfigurable Huygens' metasurface with controllable active elements, achieving simultaneous multi-spot control and reprogramming at microwave frequencies.

Findings

Successfully demonstrated a reconfigurable microwave metalens

Achieved simultaneous control of multiple focal spots

Enabled dynamic reprogramming with high efficiency

Abstract

Metasurfaces enable a new paradigm of controlling 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 re-programmable functions are still very challenging, forcing researchers to realize just one or few of the aforementioned features in one design. In this study, we report a subwavelength reconfigurable Huygens' metasurface realized by loading it with controllable active elements. Our proposed design provides a unified solution to the aforementioned challenges of real-time local reconfigurability of efficient Huygens' metasurfaces. As one exemplary demonstration, we experimentally realized a reconfigurable metalens at the microwave frequencies which, to our best knowledge, demonstrates for the first time that multiple and complex focal spots can be controlled simultaneously at distinct spatial positions and re-programmable 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.