- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Broadband and highly efficient polarization conversion in infrared region using plasmonic metasurfaces
摘要： We propose two categories of broadband, high-efficiency reflective wave plates operating in the infrared region. The first one is a half-wave plate (HWP) composed of single L-shaped antennas, and the second one is a quarter-wave plate (QWP) composed of double L-shaped antennas. In contrast to the conventional wave plate, the proposed QWP is a simple combination of two HWPs. We theoretically analyze the feasibility of the design and simulate the conversion efficiency. The proposed HWP and QWP are highly efficient with bandwidths of 1670–2791 nm and 1592–3867 nm, respectively. The novel design may be beneficial for the implementation of polarization conversion devices.
关键词： Metasurfaces,Infrared region,Polarization converter
更新于2025-09-19 17:13:59
-
[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Tri-band Linear to Circular Polarization Converter based on Transmissive Metasurfaces
摘要： Multi-band operation for terahertz wireless systems is a challenging problem. We propose a tri-band linear to circular polarization converter in the terahertz regime using metasurfaces in transmission modes. The converter is composed of bi-layered metasurfaces separated by a dielectric spacer. Three bands (0.54-0.804, 1.904-2.476, and 2.96-3.884 THz) of linear to circular polarization conversion (LCPC) are achieved due to the superposition of the two transmitted components with a near 90° phase difference. Idea is verified by HFSS and paves a way to the design of multi-band transmissive linear to circular polarization converter.
关键词： linear to circular polarization converter,transmission modes,metasurfaces,terahertz,Multi-band operation
更新于2025-09-16 10:30:52
-
Design of broadband polarization converter for terahertz waves
摘要： A broadband reflective polarization converter is proposed. The unit cell of polarization converter is composed of a single-split resonant ring, a double-split resonant ring, a dielectric substrate and a metallic ground. The simulated results show that the polarization converter can convert x-polarized waves into y-polarized waves and obtain a broadband polarization conversion from 0.501 0 THz to 1.390 0 THz with the polarization conversion ratio (PCR) beyond 80% at normal incidence. Moreover, the surface current distributions are investigated to explain the polarization conversion mechanism. Finally, a good agreement is achieved between simulated and measured results. The polarization converter can be applied in terahertz imaging, communication and stealthy technology.
关键词： metasurface,terahertz waves,polarization conversion ratio,broadband,polarization converter
更新于2025-09-10 09:29:36
-
Optical control of polarized terahertz waves using dye-doped nematic liquid crystals
摘要： We propose an optically tunable terahertz (THz) polarization converter based on use of a dye-doped nematic liquid crystal (LC). The dye-doped LC exhibits a photothermally-induced nematic-isotropic phase transition under irradiation by a laser beam with a wavelength that lies within the absorption band of the dye. We investigate the transmission spectra and the polarization-conversion properties of the dye-doped LC cell with twisted alignment using THz time-domain spectroscopy. The polarization state of a THz wave transmitted through the proposed dye-doped LC cell can be controlled using the laser beam irradiation based on the photothermal effect. The experimental results also demonstrate that optical control of this dye-doped LC cell offers an advantage in terms of response speed when compared with voltage-based control of LC cells via their electrodes. The dye-doped LC proposed in this study presents the possibility that a variety of LC-based THz elements with optical tunability may be realized.
关键词： terahertz,polarization converter,liquid crystal,optical control,photothermal effect
更新于2025-09-10 09:29:36
-
[IEEE 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - Auckland, New Zealand (2018.8.5-2018.8.8)] 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - A Metasurfaced Pyramidal Horn Antenna for Circularly-Polarized Applications
摘要： A high-gain circularly-polarized pyramidal horn antenna is developed by loading a thin metasurface linear-to-circular polarization (LP-CP) converter on the aperture of a standard pyramidal horn. The LP-CP converter is composed of two identical dielectric slabs, sandwiched by three subwavelength metallic element arrays. By placing the metasurface LP-CP converter on the aperture of a standard horn antenna, the linearly-polarized wave emitted by the horn can be converted to be circularly-polarized, without changing much other radiation performance. An example is given of a metasurface LP-CP converter and horn (metahorn) antenna that exhibits high gain and circular polarization. The measurement of this metahorn shows a 3-dB axial ratio bandwidth of 8.7%, with a maximum gain reduction of 2 dB, compared with that of the original air-filled standard pyramidal horn.
关键词： pyramidal horn,polarization converter,circularly-polarized,metasurface
更新于2025-09-09 09:28:46
-
[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Bi-layer Metamaterial based Broadband Linear Polarization Converter under Two Coherent Beam Illumination
摘要： We demonstrate a bi-layer metamaterial structure with mirror symmetry that acts as a linear polarization converter under two-antisymmetric-beam illumination. Its high performance, including broad bandwidth, high transmittance and high efficiency, originates from the combination of two interference processes: the Fabry-Pérot-like cavity effect between two metallic patterned layers and coherent excitations of spatially separated subwavelength resonators. Terahertz (THz) experiments show good agreement with numerical simulations.
关键词： Fabry-Pérot-like cavity,broadband,THz experiments,linear polarization converter,high efficiency,bi-layer metamaterial,coherent excitations,high transmittance
更新于2025-09-09 09:28:46
-
A tunable ultra-broadband linear-to-circular polarization converter containing the graphene
摘要： In this paper, a tunable ultra-broadband linear-to-circular polarization converter (LCPC) in terahertz regime containing the graphene is proposed, which are composed of two "I"-shaped gold resonators, a strip-shaped graphene sheet, two dielectric layer and a bottom gold reflector. The proposed LCPC can convert the linearly polarized wave into circularly polarized wave in an ultra-broadband frequency range which can be expanded to the lower frequencies by decreasing the Fermi energy (??f ) of the graphene in terahertz region. When ??f = 0.4 eV, 0.6 eV, 0.8 eV and 1.0 eV, the axial ratio band of the proposed LCPC which is less than 3 dB are covered 0.9248～2.2880 THz, 0.9408～2.2893 THz, 0.9665～2.2803 THz, and 0.9746～2.2780 THz, whose relative bandwidths are 84.86%, 83.49%, 80.93% and 80.15%, respectively. The maximum 3 dB axial ratio band is located at 0.9248～2.2880 THz and its relative bandwidth is 84.86% at the case of ??f = 0.4 eV. The polarization conversion rate curves, reflection phase curves, surface current and electric field diagrams are analyzed to elucidate the physical characteristics of the presented LCPC. In addition, the effect of parameters a, b and c on the axial ratio band are also discussed, respectively. This design offers an effective way to realize the reconfigurable LCPC, and also has enormous potential value in realizing the THz devices.
关键词： Graphene,Ultra-broadband,Tunable line-to-circular polarization converter
更新于2025-09-04 15:30:14
-
Compact High-Efficiency Broadband Metamaterial Polarizing Reflector at Microwave Frequencies
摘要： A compact highly efficient broadband microwave polarizing reflector, employing a quasi-2-D metamaterial composed of a single layer of square split-ring resonators, is presented and its performance is reported. Numerical and experimental results show a cross-polarization average polarization conversion ratio of greater than 90% for normal incident linearly polarized waves over a frequency range of 8.2–23 GHz. Due to multiple resonances occurring over this frequency range, the polarizing reflector presents both broadband performance and high polarization conversion efficiency. Transfer matrix and equivalent surface impedance theory and modeling are discussed to explain the physical underpinnings of the reflector’s multiresonance behavior. These physical mechanisms are further analyzed by examination of simulated surface current distributions. The reflector is expected to be employed in applications where the control of the signal polarization is of central importance.
关键词： transfer matrix,polarization converter,Broadband,equivalent surface impedance
更新于2025-09-04 15:30:14