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1.
A metal-graphene hybrid metasurface polarization converter is designed in this Letter.The unit cell of the hybrid metasurface is composed of a butterfly-shaped structure whose branches are connected by multi-layer graphene sheets.The proposed device can be reconfigured from linear-to-circular polarization to cross-polarization by changing the Fermi energy of graphene.The simulation results show that for three-layer graphene,the device acts as a linear-to-circular polarization converter when EF=0 eV and switches to a cross-polarization converter when EF=0.5 eV.Compared with single-layer graphene,the device with three-layer graphene can maintain the cross-polarization conversion performance under low Fermi energy.Furthermore,two equivalent circuits in the x and y directions are developed to understand the working mechanism of the device. 相似文献
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Dispersion characteristics of two-dimensional unmagnetized dielectric plasma photonic crystal 总被引:1,自引:0,他引:1
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This paper studies dispersion characteristics of the
transverse magnetic (TM) mode for two-dimensional unmagnetized
dielectric plasma photonic crystal by a modified plane wave method.
First, the cutoff behaviour is made clear by using the
Maxwell--Garnett effective medium theory, and the influences of
dielectric filling factor and dielectric constant on effective
plasma frequency are analysed. Moreover, the occurence of large gaps in
dielectric plasma photonic crystal is demonstrated by comparing the
skin depth with the lattice constant, and the influence of plasma
frequency on the first three gaps is also studied. Finally, by using
the particle-in-cell simulation method, a transmission curve in the
\Gamma -X direction is obtained in dielectric plasma photonic
crystal, which is in accordance with the dispersion curves
calculated by the modified plane wave method, and the large gap between
the transmission points of 27~GHz and 47~GHz is explained by
comparing the electric field patterns in particle-in-cell
simulation. 相似文献
4.
该文提出了一种基于石墨烯的宽带可调谐吸波器,该器件是由网格型石墨烯结构、介质层及金属地板组成。采用CST软件对器件的性能进行了仿真分析,仿真结果显示,当石墨烯费米能级时,在2.97~3.74 THz内,器件对电磁波吸收率达90%。另一方面,器件的工作频率可通过改变石墨烯的费米能级进行动态调控。当石墨烯的费米能级从0.3 eV变到0.8 eV时,器件的工作频率在2.60~4.55 THz内调谐,相对调谐带宽为56%,且在整个调谐频率范围内,器件对电磁波的吸收率始终高于90%。此外,器件的工作性能对入射电磁波的偏振方向和入射角不敏感,因此,该器件在太赫兹成像、太赫兹检测和隐身技术等领域有潜在的应用价值。 相似文献
5.
In this paper, a high refractive index metamaterial(HRM), whose element is composed of bilayer square patch(BSP)spaced by a dielectric plate, is proposed. By reducing the thickness of the dielectric plate and the gap between adjacent patches, the BSP can effectively enhance capacitive coupling and simultaneously suppress diamagnetic response, which significantly increases the refractive index of the proposed metamaterial. Furthermore, the high refractive index region is far away from the resonant region of the metamaterial, resulting in broadband. Based on these characteristics of BSP, a gradient refractive index(GRIN) lens with thin thickness(0.34λ_0, where λ_0 is the wavelength at 5.75 GHz) is designed.By using this lens, we then design a circularly polarized horn antenna with high performance. The measurement results show that the 3-d B axial ratio bandwidth is 34.8%(4.75 GHz~ 6.75 GHz) and the antenna gain in this frequency range is increased by an average value of 3.4 dB. The proposed method opens up a new avenue to design high-performance antenna. 相似文献
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一种频带展宽的小型化左手偶极子天线的设计 总被引:1,自引:1,他引:0
左手传输线加载偶极子(简称左手偶极子)可以有效实现天线的小型化,但是这种天线通常带宽窄、效率低。通过采用一种渐变的梯形网络结构代替传统的非渐变的结构形式来改善天线的阻抗特性,设计了四单元的左手偶极子天线,进而拓展了天线的带宽,天线总长度为0.2。仿真和实物测试结果显示:天线同时工作在–1阶和–3阶谐振模式,|S11|≤–10 dB的阻抗带宽达到6.5%,在工作频段内(571~610 MHz),天线的增益不小于–4.25 dBi,效率大于25%。 相似文献
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提出了一种变态光子带隙结构,研究了由这种结构构成的周期慢波系统的Cherenkov辐射源的特性. 利用高频仿真软件以及三维粒子模拟软件对变态及常态光子带隙慢波系统中类TM01模的色散特性及注-波互作用物理过程进行了模拟研究. 结果表明,在变态光子带隙慢波系统中,类TM01模纵向场分量沿角向分布均匀性得到明显改善,能有效抑制非对称模式,提高输出频谱纯度及注-波互作用效率.
关键词:
Cherenkov辐射源
变态光子带隙结构
慢波系统
三维粒子模拟 相似文献
8.
Three-dimensional simulation of Ka-band relativistic Cherenkov source with metal photonic-band-gap structures 总被引:1,自引:0,他引:1
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This paper presents a three-dimensional particle-in-cell (PIC) simulation of a Ka-band relativistic Cherenkov source with a slow wave structure (SWS) consisting of metal photonic band gap (PBG) structures. In the simulation, a perfect match layer boundary is employed to absorb passing band modes supported by the PBG lattice with an artificial metal boundary. The simulated axial field distributions in the cross section and surface of the SWS demonstrate that the device operates in the vicinity of the π point of a TM01-like mode. The Fourier transformation spectra of the axial fields as functions of time and space show that only a single frequency appears at 36.27 GHz, which is in good agreement with that of the intersection of the dispersion curve with the slow space charge wave generated on the beam. The simulation results demonstrate that the SWS has good mode selectivity. 相似文献
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本文通过对比频散特性和滞回特性,计算界面态密度Dit和有效边界缺陷密度ΔNbt,分析界面缺陷和漏电流等方法,系统的研究了In0.53Ga0.47As表面氮化和硫钝化对其Al/Al2O3/InGaAs结构MOS电容特性的影响。实验结果表明,这两种方法都能够在InGaAs表明形成一层界面钝化层。相比较于未处理的样品,经过氮气等离子体处理的样品表现出较好的界面特性,得到了最小的积累区频散、滞回电压,以及良好的I-V性能。经过(NH4)2Sx处理的样品则获得了最小的平带电压区频散以及最低的界面态密度Dit=2.6E11cm-2eV-1. 相似文献
10.
提出了等离子体填充的二维金属光子晶体模型,采用时域有限差分法研究了等离子体填充的二维正方晶格和三角晶格金属光子晶体的色散和带隙特性.对比分析了两种结构中等离子体密度对TM及TE模式传播特性的影响规律.研究发现,由于背景等离子体的引入,二维金属光子晶体的色散曲线明显往高频方向移动,等离子体密度的改变可同时控制TE和TM模的带隙位置和禁带宽度.这些特性使得二维等离子体金属光子晶体在设计可调谐光子晶体器件方面具有潜在的应用价值. 相似文献