Structured Surfaces for Generation of Negative Index of Refraction

Materials with negative index of refraction have properties that are not naturally available. Such properties can be used to develop novel devices like the superlens which can surpass the diffraction limit. Optical cloaking can be achieved through this negative refractive index method. This article reviews the progress made in the area of negative refractive index materials from the first generation of negative electrical permittivity to the demonstration of negative index of refraction at optical frequency, with the relevant discussion on the physics of these materials. The prime focus of this article is on experimental demonstrations and fabrication related issues of negative refractive index materials which makes use of structured surfaces.     

Breather Lattice Solutions to Negative mKdV Equation

In this paper, dependent and independent variable transformations are introduced to solve the negative mKdV equation systematically by using the knowledge of elliptic equation and Jacobian elliptic functions. It is shown that different kinds of solutions can be obtained to the negative mKdV equation, including breather lattice solution and periodic wave solution.     

基于类耿氏效应的低密度聚乙烯中空间电荷包行为的模拟仿真

低密度聚乙烯材料中的空间电荷包现象通常会引起严重电场畸变而影响其击穿特性. 本文借鉴半导体中的耿氏效应的负微分迁移率机理来描述电荷包的形成机理,并结合载流子的注入条件及体内陷阱对电荷迁移的影响等因素,对文献中报道的两类外加场强不同且迁移趋势各异的空间电荷包行为进行了模拟仿真,模拟的电荷包大小随电场变化规律,电荷包迁移速率随时间变化规律等与相应实验结果符合.模拟结果表明,产生耿氏效应的负微分迁移率是造成电荷包非弥散传输的主要原因,其与材料电极注入情况及体内陷阱态的共同作用导致了空间电荷包行为迁移的多样性. 关键词： 空间电荷包 耿氏效应 模拟仿真 负微分迁移率     

第十五届全国原子与分子物理学术会议:大尺寸贵金属纳米团簇热力学性质的分子动力学模拟研究

采用分子动力学方法和原子嵌入模型势模拟了大尺寸金（n=1136--1556）、银（n=1088--1724）、铜（n=1000--1600）、铂（n=1004--1800）原子纳米团簇的熔化过程,得出了相应纳米团簇的势能随温度的变化曲线以及热容量随温度的变化曲线,研究了各种原子纳米团簇熔点与其团簇尺寸的关系。模拟结果表明团簇的熔点随团簇尺寸增大而升高,并逐渐向大块晶体靠拢。所有纳米团簇在熔化过程中在熔点附近都出现负热容现象,通过对团簇熔化前后结构的比较研,分析了导致这种现象的原因。     

Coherent control of negative refraction based on local-field enhancement and dynamically induced chirality

This paper studies the electromagnetic response of a coherently driven dense atomic ensemble to a weak probe.It finds that negative refraction with little absorption may be achieved in the presence of local-field enhanced interaction and dynamically induced chirality.The complex refractive index governing the probe refraction and absorption depends critically on the atomic density,the steady population distribution,the coherence dephasings,and the frequency detunings,and is also sensitive to the phase of the driving field because the photonic transition paths form a close loop.Thus,it can periodically tune the refractive index at a fixed frequency from negative to positive values and vice versa just by modulating the driving phase.Moreover,the optimal negative refraction is found to be near the probe magnetic resonance,which then requires the electric fields of the probe and the drive being on two-photon resonance due to the dipole synchronisation.     

Negative differential resistance behaviour in N-doped crossed graphene nanoribbons

By using first-principles calculations and nonequilibrium Green’s function technique, we study elastic transport properties of crossed graphene nanoribbons. The results show that the electronic transport properties of molecular junctions can be modulated by doped atoms. Negative differential resistance (NDR) behaviour can be observed in a certain bias region, when crossed graphene nanoribbons are doped with nitrogen atoms at the shoulder, but it cannot be observed for pristine crossed graphene nanoribbons at low biases. A mechanism for the negative differential resistance behaviour is suggested.     

关于光学实验中望远镜与光杠杆的调节探讨

在关于望远镜的光杠杆调节中通常只给出了对光杠杆及望远镜的上下位置的调节,而忽视了望远镜和光杠杆的左右调节。给出了望远镜和光杠杆的调节中左右位置的调节原理和调节操作方法,从而使望远镜和光杠杆的调节更具有目的性,使实验进行的更加快速和准确。     

Band rules for the frequency spectra of three kinds of aperiodic photonic crystals with negative refractive index materials

By means of the theory of electromagnetic wave propagation and transfer matrix method, this paper investigates the band rules for the frequency spectra of three kinds of one-dimensional (1D) aperiodic photonic crystals (PCs), generalized Fibonacci GF(p,1), GF(1,2), and Thue--Morse (TM) PCs, with negative refractive index (NRI) materials. It is found that all of these PCs can open a broad zero-? gap, TM PC possesses the largest zero-? gap, and with the increase of p, the width of the zero-? gap for GF(p,1) PC becomes smaller. This characteristic is caused by the symmetry of the system and the open position of the zero-? gap. It is found that for GF(p,1) PCs, the possible limit zero-? gaps open at lower frequencies with the increase of p, but for GF(1,2) and TM PCs, their limit zero-? gaps open at the same frequency. Additionally, for the three bottom-bands, we find the interesting perfect self-similarities of the evolution structures with the increase of generation, and obtain the corresponding subband-number formulae. Based on 11 types of evolving manners Q_i(i=1,2,....,11) one can plot out the detailed evolution structures of the three kinds of aperiodic PCs for any generation.     

脉冲电场介导的植物空气负离子发射的倍增效应及其意义

介绍了空气负离子(NAI)的物理概念及其在空气净化中的作用,讨论了正常生态条件下空气中NAI的来源.通过实验结果说明了脉冲电场可以使植物产生NAI发射的倍增效应,分析了其产生的机理.     

石英晶体右旋光与左旋光折射率差的温度特性

利用Jones矩阵,从理论上分析了石英晶体的旋光特性。在-10～60℃的温度范围内,实验测试了石英晶体的旋光角随温度的变化关系,并得出了石英晶体右旋圆偏振光与左旋圆偏振光折射率差随温度的变化关系。结果表明,对单色光来说,石英晶体右旋光与左旋光折射率差随温度的升高而增加,也就是说,石英晶体的旋光率随温度变化的这一特性是由晶体的右旋圆偏振光与左旋圆偏振光的折射率差随温度的变化引起的。