Nonvolatile Switchable Broadband Polarization Conversion with Wearable Terahertz Chalcogenide Metamaterials

Abstract

Regarding these applications, high-performance THz devices become essential for manipulating THz light. One crucial group of devices was associated with driving polarization, such as wave retarders, polarizers, and rotators of polarization. [2] Conventional polarization converters used total internal reflection or birefringence effects in polymers and crystals, [3,4] which produced phase retardation. Those wave converters demanded a relatively long propagation distance to achieve the necessary phase accumulation between two orthogonal polarization constituents, leading to bulky size. [3,5] Hence, these approaches were not proper for device integration and miniaturization. Lightweight and compact polarization converters are needed to manipulate the polarization state of the THz wave. In the last decade, metamaterials, i.e., artificial ultrathin subwavelength resonators array, have attracted increasing attention owing to their extraordinary electromagnetic characteristics unavailable in natural materials. [6,7] It opened up meaningful chances, including an alternative approach to control the polarization of light. Recently, the THz metamaterials have made significant progress. [8][9][10] Particularly, polarimetric meta-devices have attracted much attention in the THz region owing to the shortage of proper natural materials for THz device applications. [11,12] To extend the function, broadband metamaterial polarization retarders or converters were highly required. For example, wideband metasurface circular polarizers were shown in the optical region using stacked nanorod arrays [13] and gold helix structures. [14] The metasurfaces have also demonstrated an ability to turn the THz wave's linear polarization state into its orthogonal state in a broadband spectrum. [12,15] For example, Grady et al. presented that between 0.8 and 1.36 THz, the cross-polarized reflection is more significant than 80%, while the co-polarized one is less than 5%. [12] The metamaterial polarization rotation was also proposed to revolve the polarization axis of a linearly polarized THz wave by any angle, and the rotation took place with a conversion efficiency of ≈0.85 at a wideband spectrum. [15] However, further developments of THz polarization meta-converters have been restricted mainly due to the lack of tunability. Their polarization conversion feature cannot be changed once the Polarization is a fundamental characteristic of light waves carrying sensitive measurement and signal communication information. Traditional schemes for advanced controlling polarization impose stringent requirements on material features and obtain merely limited performance. Integration of diversified and switchable functions into monolithic metamaterials has become a rising research field, particularly for the terahertz (THz) spectrum. However, the study on the switchable and wearable polarization meta-converter with nonvolatile operation stays unexplored. Here, the switching of metamaterialinduced ultra-broadband and very efficient reflective linear polarizati...

Switchable ultra-broadband absorption and polarization conversion terahertz metasurface

“…式中ε∞为高频极限介电常数，ε∞=12；γ为碰撞频率，γ=5.57×10 13 所设计的超表面可以通过磁控溅射技术 [23] 和电子束光刻 [24] 进行制备。制备 过程如图 9 所示，具体步骤如下。(a)利用磁控溅射技术在硅衬底上沉积金层；(b)…”

Dispersion‐Compensated Terahertz Ultra‐Broadband Quarter and Half Wave Plates in a Dielectric‐Metal Hybrid Metadevice

“…In recent years, artificial electromagnetic microstructures have opened up a new way for the development of THz devices, such as metamaterials, metasurfaces, and topological photonic crystals. [ 16–26 ] Multifunctional THz broadband polarization devices with excellent performance can be realized by introducing artificial anisotropy into unit cells or by structural parameter design, including linear‐linear, linear‐circular, and circular‐circular polarization conversion devices. [ 27–33 ] In terms of bandwidth, it could be extended by simply stacking multiple resonant modes at different frequencies in a unit cell of metamaterials.…”

Magnetically Reconfigurable Toroidal Metasurfaces

“…[6][7][8][9] In this context, the artificially designed metamaterials and their 2-dimensional analog DOI: 10.1002/adom.202303045 (metasurfaces) are capable of confining and manipulating the electromagnetic radiations in an unprecedented way. [10][11][12][13] These artificially engineered photonic meta structures, which can operate beyond diffraction limit has shown a wide range of applications, such as artificial magnetism, [14,15] cloaking, [16][17][18] switches, [19][20][21] absorbers and sensors, [22][23][24][25][26] notable contribution in quantum computation, [27,28] exceptional points, [29] as well as extensive applications in nonlinear optics, [30,31] etc. At the fundamental level, these metasurfaces are categorized in terms of the excited multipoles, such as electric, magnetic, toroidal, and higher-order poles depending upon their induced charge and current distributions.…”