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Ultra-wideband reflective polarization converter based on anisotropic metasurface

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Chinese Physics B 2016年第8期25卷 402-406页

作者：吴家梁林宝勤达新宇 Information and Navigation College Air Force Engineering University

In this paper, we propose an ultra-wideband reflective linear cross-polarization converter based on anisotropic metasurface. Its unit cell is composed of a square-shaped resonator with intersectant diagonal and metallic ground sheet separated by dielectric substrate. Simulated results show that the converter can generate resonances at four frequencies under normal incident electromagnetic（EM） wave, leading to the bandwidth expansion of cross-polarization reflection. For verification,the designed polarization converter is fabricated and measured. The measured and simulated results agree well with each other, showing that the fabricated converter can convert x- or y-polarized incident wave into its cross polarized wave in a frequency range from 7.57 GHz to 20.46 GHz with a relative bandwidth of 91.2%, and the polarization conversion efficiency is greater than 90%. The proposed polarization converter has a simple geometry but an ultra wideband compared with the published designs, and hence possesses potential applications in novel polarization-control devices.

关键词： polarization converter anisotropic metasurface ultra-wideband

High efficiency of broadband transmissive metasurface terahertz polarization converter

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Chinese Physics B 2023年第2期32卷 250-263页

作者：周强国李洋李永振姚娘娟黄志明 State Key Laboratory of Infrared Physics Shanghai Institute of Technical PhysicsChinese Academy of SciencesShanghai 200083China Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310024China Institute of Optoelectronics Fudan UniversityShanghai 200438China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Space Active Opto-Electronics Technology Shanghai Institute of Technical PhysicsChinese Academy of SciencesShanghai 200083China

Terahertz wave is between microwave and infrared bands in the electromagnetic spectrum with the frequency range from 0.1 THz to 10 THz. Controlling and processing of the polarization state in terahertz wave are the focus due to its great influence on the characteristics. In this paper, a transmissive metasurface terahertz polarization converter is designed in 3D structure with an upper surface of ruler-like rectangular, an intermediate dielectric layer and a lower surface of metal grid wires. Numerical simulations of the converter show that the polarization conversion ratio(PCR) is above 99.9% at 0.288 THz–1.6 THz, the polarization rotation angle(PRA) is close to 90° at 0.06 THz–1.4 THz, and the ellipticity angle(EA) is close to 0° at 0.531 THz–1.49 THz. The origin of the efficient polarization conversion is explained by analyzing the electric field intensity, magnetic field intensity, surface current, electric field energy density, and magnetic field energy density distributions of the converter at 1.19 THz and 0.87 THz, which are consistent with the energy transmittance and transmittance coefficient. In addition, the effects of different thickness and material of intermediate layer, thickness of upper surface material, polarized wave incidence angle, and metasurface materials on the performance of the polarization converter are discussed, and how they affect the conversion performance of the polarization converter are also *** results provide a strong theoretical basis and technical support to develop high performance transmission-type terahertz polarization converters, and play an important role to promote the development of terahertz science and technology.

关键词： terahertz polarization converter metasurface transmittance

Wideband linear-to-circular polarization conversion realized by a transmissive anisotropic metasurface

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Chinese Physics B 2018年第5期27卷 227-233页

作者： Bao-Qin Lin Jian-Xin Guo Bai-Gang Huang Lin-Bo Fang Peng Chu Xiang-Wen Liu School of Information Engineering Xijing University Xi＇ an 710051 China

We propose a metasurface which consists of three conductive layers separated by two dielectric layers. Each conductive layer consists of a square array of square loop apertures, however, a pair of corners of each square metal patch surrounded by the square loop apertures have been truncated, so it becomes an orthotropic structure with a pair of mutually perpendicular symmetric axes u and v. The simulated results show that the metasurface can be used as a wideband transmission-type polarization converter to realize linear-to-circular polarization conversion in the frequency range from12.21 GHz to 18.39 GHz, which is corresponding to a 40.4% fractional bandwidth. Moreover, its transmission coefficients at x-and y-polarized incidences are completely equal. We have analyzed the cause of the polarization conversion, and derived several formulas which can be used to calculate the magnitudes of cross-and co-polarization transmission coefficients at y-polarized incidence, together with the phase difference between them, based on the two independent transmission coefficients at u-and v-polarized incidences. Finally, one experiment was carried out, and the experiment and simulated results are in good agreement with each other.

关键词： polarization converter metasurface circular polarization