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A Reconfigurable Active Huygens' Metalens
Ke Chen, Yijun Feng, Francesco Monticone, Junming Zhao, Bo Zhu, Tian Jiang, Lei Zhang, Yongjune Kim, Xumin Ding, Shuang Zhang, Andrea Alù, Cheng-Wei Qiu
TL;DR
Existing resonators lack tunable or reconfigurable responses, limiting multifunctional wave control. The paper demonstrates an actively tunable Huygens’ metalens that simultaneously realizes multiple focal spots at distinct positions, moves them along designed trajectories, and supports advanced functionalities.
Problem
Metallic or dielectric resonators lack tunable or reconfigurable responses, leaving a gap in dynamically controllable metasurface functionality.
Method
The paper demonstrates an actively tunable Huygens’ metalens and experimentally verifies its performance using near-field scanning.
Results
The metalens simultaneously realizes multiple focal spots at distinct spatial positions and moves them along pre-designed trajectories with high efficiency and fast response time.
Takeaways & Limitations
The demonstrated reconfigurability supports the creation of various advanced metasurface functionalities.
Takeaways & Limitations
The achieved efficiency is reduced by loss and deviations in phase and amplitude introduced by the active elements.
Abstract
from arXiv · showhide
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.
Experimental Section
Experimental verification uses a parallel-plate waveguide near-field scanning system to measure the proposed active metalens. The setup generates an incident plane wave and maps the planar waveguide’s electric field with a monopole detector and microwave vector network analyzer.
- Measurement setup: A parallel-plate waveguide near-field scanning system is used for experimental verification of the proposed active metalens.The sample plate is inserted between metallic plates to satisfy the array’s periodic boundary condition.
- Measurement setup: A monopole antenna, corner, and parabolic reflector generate the incident plane wave.The sample plate remains orthogonal to the metallic plates during measurement.
- Measurement setup: Another monopole antenna maps the electric field inside the planar waveguide using a microwave vector network analyzer.The analyzer is an Agilent N5244A.