Manipulating surface plasmon waves by transformation optics:Design examples of a beam squeezer,bend,and omnidirectional absorber

We present several design examples of how to apply transformation optics and curved space under coordinate transformation to manipulating the surface plasmon waves in a controlled manner.We demonstrate in detail the design procedure of the plasmonic wave squeezer,in-plane bend and omnidirectional absorber.We show that the approximation method of modifying only the dielectric material of a dielectric-metal surface of the plasmonic device could lead to acceptable performance,which facilitates the fabrication of the device.The functionality of the proposed plasmonic device is verified using three-dimensional full-wave electromagnetic simulations.Aiming at practical realization,we also show the design of a plasmonic in-plane bend and omnidirectional absorber by an alternative transformation scheme,which results in a simple device structure with a tapered isotropic dielectric cladding layer on the top of the metal surface that can be fabricated with existing nanotechnology.     

基于分形的吸波材料及其在微带天线中的应用

在方形贴片完美吸波材料的基础上,通过Minkowski分形和开槽,设计了一种新型完美吸波材料,并分析了其吸波原理.将该材料加载于微带天线,用于减缩天线带内雷达散射截面(RCS).仿真结果表明,相比于方形贴片吸波材料,设计材料的谐振频率下降了8.6％,最大吸波率达99.97％.加载该材料后,天线的辐射性能没有降低,而其带内RCS得到有效减缩.实测结果与仿真结果较为吻合,表明了该材料可以用于微带天线的带内隐身.     

表面等离激元研究新进展

随着理论研究的深入和现代微加工技术的进步,对支持表面等离激元的金属微纳结构体系的研究已形成了一门新兴学科方向,即表面等离激元光子学。由于表面等离激元具有独特的光学特性,在数据存储、超分辨成像、光准直、太阳能电池、生物传感器以及负折射材料等方面有着重要的应用前景,成为当前广受国内外学者重视的热点研究领域之一。本文对表面等离激元的特点、基本现象,以及其带来的新颖效应及其应用研究前景的最新发展进行了介绍。     

S波段超材料完全吸收基板微带天线

设计了基于树枝状结构单元模型的完全吸波超材料,并将此树枝状结构完全吸波超材料作为微带天线的基板,制备了S波段超材料完全吸收基板微带天线,模拟和实验结果表明,窄带和宽带完全吸波超材料都可提高微带天线的定向性和增益,性能得到了明显改善.经过优化设计S波段超材料完全吸收基板微带天线的增益相比普通微带天线提高了1.8 dB,相当于有效辐射功率提高了51%.表明将完全吸波超材料作为天线的基板,可以明显改善天线性能. 关键词： 树枝状结构 微带天线 完全吸波材料 增益     

一种新颖的变异开口谐振环双频带磁谐振特异材料

根据磁谐振等效电路原理,设计出了工作在X波段的基于变异开口谐振环(split ring resonators)结构的新型双频带磁谐振特异材料.由于内外环间具有弱耦合的优越特性,所提出的磁谐振特异材料的两个工作频点可以较为方便地调节.该研究成果为特异材料的多频带、宽带化提供有益的的研究思路和设计方法. 关键词： 磁谐振特异材料 双频带 弱耦合     

A flexible ultra-broadband metamaterial absorber working on whole K-bands with polarization-insensitive and wide-angle stability

For potential military applications, a flexible metamaterial absorber (MMA) working on whole K-bands with total-thickness of 3.367 mm, ultra-broadband, polarization-insensitive, and wide-angle stability is presented based on frequency-selective surface (FSS). The absorber is composed of polyvinyl chloride (PVC) layer, polyimide (PI) layer, and poly tetra fluoro ethylene (PTFE) layer, with a sandwich structure of PVC-PI-PTFE-metal plate. Periodic conductive patterns play a crucial role in the absorber, and in traditional, it is designed on the upper surface of PI layer to form LC resonance. Different from commonly absorber, all the patterns are located on the lower surface of the PI layer in this work, and hence the impedance matching and absorptivity are improved in this purposed absorber. The flexible absorber with patterns on lower surface of the PI layer is compared with that on upper surface of the PI layer, the difference and the reasons are explained by absorption mechanism based on equivalent circuit model, and surface current density and electric field distribution are used to analyze resonance peaks. Absorptivity is greater than 90% in a frequency range of 10.47 GHz-45.44 GHz with relative bandwidth of 125.1%, covering the whole Ku, K, Ka, and some of X, U bands, especially containing the whole K bands from 12 GHz to 40 GHz. Radar cross section (RCS) is reduced at least 10 dB in 11.48 GHz-43.87 GHz frequency ranges, and absorption remained about 90% when the incident angle changed from 0° to 55°. The purposed absorber is fabricated, measured, and experiment results show good agreement with theoretical analysis and numerical simulation. After bonded on outer surface of different cylinders with diameters of 200 mm and 100 mm, the absorption of MMA is approximately reduced 10% and 20% respectively, which shows good conformal character with surface of various curvatures. Due to the attractive performance on strong absorption in the whole K-bands, flexible and easy conformal, our design exhibits broad potential application in radar stealth and sensors.     

一种超介质单元加载的电小天线

根据等效介电常数为负(epsilon-negative,ENG)的超介质层加载偶极子天线可增强辐射效率的原理,提出一种新型电小天线。采用"门"型单元结构对中心频率为400MHz的电单极子加载,在提高天线辐射效率的同时极大地减小天线尺寸。测试结果表明,"门"型电小天线的增益与传统0.25λ单极子天线相当,比同尺寸单极子天线提高8dB,实际天线尺寸仅为0.08λ。     

Photonic band gap in a one-dimensional periodic structure with semiconductor metamaterial in the near infrared

We construct a one-dimensional photonic crystal (1DPC) by use of semiconductor metamaterial in the near infrared which is composed of Al-doped ZnO (AZO) and ZnO and dielectric material. The expressions of transmittance and field distribution are deduced by transfer matrix method, and the dispersion curves of anisotropic permittivity of semiconductor metamaterial are analyzed at different ratio of AZO and ZnO. At last simulation results are given to analyze the influence of thickness of dielectric material and incident angle on the transmittance of the proposed PC.     

极薄宽角度平面超材料吸波体仿真与实验验证

仿真和实验验证了厚度极薄的平面结构超材料吸波体, 该吸波体采用加载交指电容的耶路撒冷十字结构, 通过增加单元间的耦合电容显著降低了其工作频率. 测试结果表明, 该超材料吸波体在1.58 GHz, 吸收率峰值为88.48%, 其厚度为2 mm, 约为1/95工作波长, 吸波体的单元尺寸为11 mm, 约为1/17工作波长. 此外, 通过金属通孔将耶路撒冷十字结构与金属底板相连接, 使其对斜入射横电和横磁极化电磁波具有宽角度吸收特性, 在60°时依然具有较高的吸收率, 且吸收峰频率几乎不发生偏移, 从而使其更具实用价值. 关键词： 极薄 宽角度 超材料吸波体     

基于VO2薄膜相变原理的温控太赫兹超材料调制器

利用二氧化钒薄膜绝缘相–金属相的相变特性, 提出了一种基于超材料的温控太赫兹调制器, 研究了相变超材料在太赫兹波段的传输特性和温控可调谐特性. 当入射太赫兹波为水平偏振或垂直偏振状态时, 器件的透过率谱线在1 THz附近呈现出两个独立的、中心频率分别为1.3 THz和1.7 THz、 带宽分别为0.2 THz和0.35 THz的 透射宽带. 当温度从40℃至80℃变化时, 两宽带的透过率发生明显的降低, 在二氧化钒的相变温度(68℃)时尤其灵敏, 对入射光的二种偏振状态, 调制深度均达到60%以上, 实现了良好的调制效果. 关键词： 太赫兹超材料 2薄膜')" href="#">VO₂薄膜 调制器 相变