左手材料设计与制备的研究进展

左手材料是一种介电常数ε和磁导率μ同时为负值的超材料,具有许多非常奇异的电磁学性质.阐述了左手材料的基本概念和性质,介绍了能够同时实现负介电常数和负磁导率的Ω形、S形和树枝等单一结构,综述了利用机械加工法和化学制备法制备的高频段负磁导率材料,以及基于耦合作用的电磁波垂直入射条件下左手材料的设计与制备方法,阐述了超材料负磁导率或左手行为的验证方法,最后展望了左手材料的应用前景.     

左手材料的研究进展与应用前景

左手材料是一种介电常数ε和磁导率μ同时为负的人工复合材料,具有许多反常的物理性质,是材料、电磁、光学等领域的热门研究方向.在结合国内外研究现状的基础上综述了左手材料的理论、结构特征、制备工艺、性能测试等,最后探讨了左手材料的发展趋势、应用前景和亟需解决的问题,以期获得对左手材料更为深刻和全面的理解.     

微波左手材料及其应用前景

左手材料是一种介电常数ε和磁导率μ同时为负的人工周期结构材料,在其中传播电磁波的群速度与相速度方向相反,从而呈现出许多奇异特性.本文介绍了左手材料的基本概念、实现原理,综述了其在理论与实验研究方面取得的最新进展、研究热点、缺陷效应及实现负折射的其它途径.最后对左手材料的应用前景进行了展望.     

左手材料设计的研究进展

阐述了左手材料的基本概念和性质,介绍了目前几种常见金属基元左手材料的结构、基本原理及特点,综述了左手材料近年来的研究动态及发展前景,指出左手材料要得到应用必须向低损耗和宽带宽方向发展。     

左手材料研究进展及应用前景

详细介绍了左手材料(同时拥有负磁导率和负介电常数)存在的理论依据、实现方法和基本电磁特性,针对其出现的新颖电磁特性介绍了它在隐身、光学和微波等领域的潜在应用,及其需进一步加强的工作和发展方向.     

左手材料的研究进展

左手材料奇异特性使得它在隐身技术、通讯技术、新型信息技术等领域有重要的应用前景.本文综述了左手材料的研究发展概况,概括了近几年来成功设计的几种左手材料的结构,并展望了左手材料今后研究的重点、发展趋势及应用前景.     

负折射率材料的研究进展

负折射率材料由于其独特的性质引起了人们极大的兴趣。介绍了负折射产生的原理及其奇特性质，着重阐述了实现负折射材料的3种主要方法：双负介质实现负折射、左手介质实现负折射和光子晶体实现负折射。分析了各种方法在实现光频段低损耗负折射材料中的可行性及纳米技术发挥的重大作用。     

负折射现象的研究进展

负折射现象是一种崭新的现象,是上个世纪60年代理论预言,直到一年前被实验证明微波照射在左手化媒质(LHM)上,折射方向不同于Snell定律所描述的.介绍了这种负折射现象研究的最新发展.着重于LHM的人工合成,理论解释以及负折射率的实验证明等几个方面,以便进一步开展这方面的工作.     

左手材料的研究与应用

本文从左手材料的概述、研究现状和应用几方面对左手材料的研究与应用进展进行了综述,希望对左手材料有一个比较全面的了解。     

基于左手材料的小型化差分微带天线

本文提出了一种应用于WiMAX的小型化差分微带天线,并通过在辐射贴片刻蚀U型缝隙的方法实现天线的小型化.与传统的半波长天线相比,该天线的尺寸为15 mm×15 mm(0.38λg×0.38λg).为了改善天线的带宽性能,设计了一种新型的哑铃型开口环金属线复合周期结构的左手材料,并将左手材料作为天线的覆层.仿真和测量结果表明:覆层左手材料的小型化差分微带天线的带宽为8.5%(3.4 GHz^3.7 GHz),峰值增益为3.8 dBi.     

Transverse localization in disordered lattices containing left-handed metamaterials

A numerical study is reported of the propagation of an initially localized wave in a one-dimensional disordered lattice composed of left-handed metamaterials. We first consider the structure made of right-handed and left-handed materials arranged periodically. By allowing disorder in the refractive index of the right-handed materials, the injected wave becomes localized as propagating through the disordered lattice. Then, we consider another photonic lattice comprising only left-handed metamaterials. It is found that the inclusion of disorder in the negative refractive index of the constituents of the system leads to transverse Anderson localization. We also investigate the dispersion effect of metamaterials on the localization behavior. It is demonstrated that inclusion of a dispersive metamaterial in the disordered photonic lattices causes the quality of transverse localization to enhance with increasing wavelength.     

Numerical study of two-dimensional metamaterial composites: the existence of a stop band

Two-dimensional metamaterial photonic crystals composed of dispersive left-handed materials and a right-handed medium were investigated. The existence of a stop band was studied by finite-difference time-domain calculations incorporated into an auxiliary differential equation (FDTD-ADE) method. The existence of a stop band was studied in the case of Drude-type dispersion responses for the dielectric permittivity and magnetic permeability of the metamaterial. A distinct stop band appears when the dispersive left-handed metamaterials are embedded in a positive-refractive-index medium and spatially isolated from each other. In contrast, the stop band is absent when the metamaterials span the entire photonic crystal.     

Microstructure formation during the annealing of iron nitrides

The thermal metastability of iron nitride was exploited to fabricate thin-film microstructures applicable to left-handed metamaterials. A granular thin film containing dispersed iron particles was prepared by post-annealing an rf-sputter-deposited Fe_0.5Al_0.5N thin film with a wurtzite-type structure in a nitrogen atmosphere at 450 °C. The obtained samples showed magnetic resonance in the microwave region. Laser direct writing was also applied in a nitrogen atmosphere to an rf-sputter-deposited Fe_0.7Al_0.3N thin film. 200 μm-wide, 300 Ω cm iron metal lines were drawn in a host nitride film of approximately 2 kΩ cm. Combining and optimizing the above negative permeability and permittivity values should provide left-handed materials with a negative refractive index.     

可调谐手征超表面电磁特性研究进展

手征超表面是由具有特定电磁响应的平面手征单元结构构成的超薄超材料,由于其具有自由控制电磁波的奇异能力而引起了极大的关注.通过在超表面设计中加入可调谐材料,可以实现其功能受外部激发控制的可调谐或可重构的超器件,为动态调谐电磁波开辟了新的道路.本文介绍了可调/可重构手征超表面电磁特性的一些理论基础,当线偏振光进入可调谐手征...     

Magnetoactive Acoustic Metamaterials

Acoustic metamaterials with negative constitutive parameters (modulus and/or mass density) have shown great potential in diverse applications ranging from sonic cloaking, abnormal refraction and superlensing, to noise canceling. In conventional acoustic metamaterials, the negative constitutive parameters are engineered via tailored structures with fixed geometries; therefore, the relationships between constitutive parameters and acoustic frequencies are typically fixed to form a 2D phase space once the structures are fabricated. Here, by means of a model system of magnetoactive lattice structures, stimuli‐responsive acoustic metamaterials are demonstrated to be able to extend the 2D phase space to 3D through rapidly and repeatedly switching signs of constitutive parameters with remote magnetic fields. It is shown for the first time that effective modulus can be reversibly switched between positive and negative within controlled frequency regimes through lattice buckling modulated by theoretically predicted magnetic fields. The magnetically triggered negative‐modulus and cavity‐induced negative density are integrated to achieve flexible switching between single‐negative and double‐negative. This strategy opens promising avenues for remote, rapid, and reversible modulation of acoustic transportation, refraction, imaging, and focusing in subwavelength regimes.     

Editorial

Presents an introduction to a special issue on metamaterials. The papers are very briefly described. In the mainstream metamaterial part of this issue, particular emphasis is placed on the so called left-handed, negative-reftactive-index (or negative index), or double negative (DNG) media. The second part of this issue concentrates on recent explorations and advances of EBG structures and related high-impedance surfaces     

A review of additive manufacturing of metamaterials and developing trends

The concept of metamaterials originates from the proposal of left-hand materials with negative refractive index, followed by which, varieties of metamaterials with kinds of fantastic properties that cannot be found in natural materials, such as zero/negative Poisson’s ratio, electromagnetic/acoustic/thermal cloaking effect, etc., were come up with. According to their application fields, the metamaterials are roughly classified into four categories, electromagnetic metamaterials, acoustic metamaterials, thermal metamaterials, and mechanical metamaterials. By designing structures and arranging the distribution of materials with different physical parameters, the function of metamaterials can be realized in theory. Additive manufacturing (AM) technology provides a more direct and efficient way to achieve a sample of metamaterial and experiment verification due to the great advantages in fabricating complex structures. In this review, we introduce the typical metamaterials in different application situations and their design methods. In particular, we are focused on the fabrication of metamaterials and the application status of AM technology in them. Furthermore, we discuss the limits of present metamaterials in the aspect of design method and the disadvantages of existing AM technology, as well as the development tendency of metamaterials.     

声学超构材料技术实用化的进展

声学超构材料是当前声学和材料学一个热门的研究领域.声学超构材料可定义为:通过对材料在特征物理尺度上进行人工设计制备,使其具有超越常规材料的声学性能的一种人工序构的复合材料.其亚波长特性、超常声学性能以及颠覆性应用的可能吸引了学界和工程界的关注.21世纪以来,随着增材制造技术的发展,声学超构材料的实验室加工与制备问题得以...