Stereo Metasurfaces for Efficient and Broadband Terahertz Polarization Conversion

Abstract

Efficient and flexible manipulation of terahertz (THz) polarization in a broadband manner using metasurfaces has attracted continuous attention in recent years. Previous studies commonly apply multilayer metallic resonators or bonded dielectric structures as the basic units, which are affected by the spacer loss or bonding difficulty and stability. Here, we propose a new design scheme based on all-metal stereo U-shaped meta-atom working in a reflection configuration. The stereo metasurface functions as an efficient and broadband THz waveplate with tailorable birefringence simply controlled by the sunken depth. Such an intriguing property is experimentally verified by a reflection-type THz half-waveplate. The polarization conversion ratio is higher than 90% with 69% relative bandwidth and over 85° angle tolerance for incidence. Furthermore, an efficient and broadband meta-grating based on Pancharatnam-Berry phase method is also experimentally demonstrated. The proposed strategy enriches the design degrees of freedom of polarization-related metasurfaces and may find broad applications in realizing various functional devices. 11974259, 61875150, 61935015); Tianjin Municipal Fund for Distinguished Young Scholars (grant No. 18JCJQJC45600).

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.…”

Reflective Polarization Conversion with Multi-Functional, Ultrathin Metasurface for Ku- and K-Band Applications

“…In this regard, polarization conversion has been utilized as single-layer [13][14][15] and multilayer [16][17][18] in microwave [19][20][21], terahertz [22][23][24][25], infrared [26][27][28], and visible [14,29] frequency regions. Based on these frequency regions, there exist modes providing easy polarization regulation of the incoming EM wave, such as reflection and transmission modes.…”

Meta-optics inspired surface plasmon devices

“…In addition, two-dimensional metamaterials composed of a planar and ultrathin array of artificial structures, i.e., metasurfaces, have shown unprecedented capabilities of manipulating electromagnetic waves at will [53–69] . In free space, practical devices of general interest, such as metalenses [70–75] , perfect absorbers [76–78] , polarization wave plates [79–85] , special beam launchers [86–89] , and holograms [90–97] , have been successfully demonstrated.…”