左手材料的研究进展

左手材料是一种介电常数ε和磁导率μ同时为负值的电磁材料.介绍了左手材料的基本原理,阐述了微波段、红外和可见光波段左手材料的实现方式,展望了左手材料的应用前景.     

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。     

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。     

左手材料的光学特性及其应用

左手材料是一种人工制备的具有亚观结构的材料，因为其独特的电磁学特性，在很多方面都具有潜在的应用价值。本文简要介绍了左手材料在完美透镜、一维光子晶体、薄板波导等方面的研究进展，对其理论研究和实验结果进行了评述，并探讨了其发展前景。     

Negative Poisson's Ratio in Modern Functional Materials

Materials with negative Poisson's ratio attract considerable attention due to their underlying intriguing physical properties and numerous promising applications, particularly in stringent environments such as aerospace and defense areas, because of their unconventional mechanical enhancements. Recent progress in materials with a negative Poisson's ratio are reviewed here, with the current state of research regarding both theory and experiment. The inter‐relationship between the underlying structure and a negative Poisson's ratio is discussed in functional materials, including macroscopic bulk, low‐dimensional nanoscale particles, films, sheets, or tubes. The coexistence and correlations with other negative indexes (such as negative compressibility and negative thermal expansion) are also addressed. Finally, open questions and future research opportunities are proposed for functional materials with negative Poisson's ratios.     

论虚空间艺术在书籍设计中的应用

介绍了虚空间艺术的定义、性质以及书籍设计中虚空间的内容。结合案例说明了虚空间在书籍设计中的功能性:创造书籍和谐与舒适的视觉美感;使书籍设计的主题突出;引发读者联想和深化书籍意境。探讨了书籍设计中对虚空间在数量、在书籍空间秩序营造、在与书籍信息节奏层次相呼应方面的要求。分析了虚空间在书籍封面、扉页、内页中的应用。从而揭示虚空间在书籍设计中的重要性。     

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.     

What is negative refraction?

We review various published definitions associated with the phenomenon of negative phase velocity propagation of electromagnetic waves in meta-media, as observed through negative refraction. For the principal definition, based on the Poynting vector and the wave vector having negative scalar product, we summarise the various material constraints that have been derived. The distinction between criteria based on the Poynting vector and the group velocity are considered, both in respect of causality, and in the context of moving media. Instances where a fully covariant definition is necessary are also identified, and compared with other results from the extant literature. Satisfaction of the NPV propagation criterion is also considered for surface plasmons.     

Metamaterial composed of different cells exhibiting a negative refraction property over multiple frequency bands

Experimental measurements are presented of the SSRR-MW (square split resonant ring and metal wire) and CSRR-MW (C split resonant ring and metal wire) samples at microwave frequencies. The geometrical shapes of the metamaterial samples are found to play an important role in determining the resonant frequency. Different cells are chosen to stack into a two-layer or a three-layer metamaterial unit to realize multiple negative passbands. The effective parameters of three one-layer models, a two-layer unit, and a three-layer unit are retrieved from the simulation data. The composed models exhibit two or more negative bands by overlapping the passbands of the original cells, and broaden the negative refraction. The recovered parameters show good agreement with theoretical analysis.     

Propagation of quantized fields through negative-index media

Dielectric materials in which both the relative permittivity, ε, and the relative permeability, μ, are negative exhibit striking optical properties, which are a consequence of the fact that the effective index of refraction in such materials is negative. Most studies of the propagation of electromagnetic fields in these media have concentrated on classical fields with well-defined phases. In contrast, I use simple fully-quantized models to illustrate how some of the striking properties of negative-index media are manifested in the propagation of single, spontaneously emitted, photons. Single-photon quantum fields do not have an absolute phase, but the examples in this paper demonstrate a quantum analog of the negative phase accumulated by classical fields as photons propagate through negative-index media. The single photons also exhibit classical reflection and transmission coefficients, as well as the expected group velocity.