左手材料平板对傍轴高斯光束聚焦特性分析

在傍轴近似下,推导出了左手材料平板聚焦系统的传输矩阵,并利用ABCD定律得到了高斯光束在左手材料中和经过平板透镜聚焦后的传输公式。高斯光束在左手材料内部和像空间的传输公式的研究表明:像高斯光束和物高斯光束束腰大小一致,即左手材料平板透镜实际上对高斯光束没有聚焦作用。研究同时表明左手材料平板对高斯光束的聚焦与几何光学成像规律完全一致,而不存在一般透镜聚焦时的焦移效应。     

左手材料的反射特性与负折射率行为

利用平板波导法研究了不同入射角度下周期排列开口谐振环负磁导率材料、周期排列金属杆负介电常数材料以及左手材料微波反射特性，并利用劈尖法研究了左手材料的负折射特性.实验结果表明：负磁导率材料反射率曲线形成反射峰，其对应的反射峰频率与材料的谐振频率一致；负介电常数材料反射率接近0dB；左手材料出现单个反射较小的反射峰，其峰值反射率随入射角度的增大而变大，即反射能力增强，且反射峰与透射峰有相对频移.劈尖法测量还表明，左手材料在9800MHz频率附近出现负折射现象，其折射率n为-0.796. 关键词： 左手材料 反射 负折射率     

Left-handed metamaterial based superlens for subwavelength imaging of electromagnetic waves

Lenses made of negative index materials have the ability to focus the propagating and evanescent components of electromagnetic waves. Such a possibility enables super resolution, in turn resulting in sharper, subwavelength size images. In this present work, we present subwavelength imaging that was obtained from a one-dimensional left-handed metamaterial (LHM) composed of alternating layers of split-ring resonators and thin wires. We investigated the effect of the thickness of LHM lenses on image size. The left-handed pass band within the negative permittivity and permeability region is shown experimentally and theoretically for different thicknesses of LHM slabs. We also studied the transmission-phase of LHMs with a different number of unit cells along the propagation direction. The phase decreases with the increasing thicknesses of LHM slabs, proving that the phase velocity is negative in the left-handed transmission band. PACS 42.25.-p; 41.20.Jb; 81.05.-t     

Broadband planar left-handed metamaterials using split-ring resonator pairs

In this paper, we showed that split-ring resonator (SRR) pairs can be used as broadband planar left-handed metamaterials (LHMs). Simulations were carried out for one layer of infinite LHM slab using SRR pairs. The results showed that by carefully adjusting dimensions of the SRR pairs, magnetic and electric resonances can be coexistent at some frequency ranges and in the frequency range where there are both negative magnetic and electric responses, there is a broad LH band. Equivalent circuits for the magnetic and electric resonance were offered to give a qualitative and quantitative explanation of the LH behaviors of LHMs using SRR pairs.     

Numerical Study of Low-Loss Cross Left-Handed Metamaterials at Visible Frequency

We present a numerical study of left-handed metamaterials （LHMs） composed of double cross pairs at visible frequency. The S-parameter retrieval method is adopted to confirm the negative refractive characteristic of this design. Compared with fishnet LHMs~ the proposed cross LHMs have a much lower loss, which will greatly facilitate practical applications. It is also found that, with the same size of resonant cells, the cross LHMs have a higher frequency than fishnet LHMs, which is explained using a simple effective LC circuit model.     

Study of a slab waveguide loaded with dispersive anisotropic metamaterials

We have numerically studied the characteristics of a slab waveguide loaded with dispersive anisotropic metamaterials. For two typical-structured metamaterials, we have analyzed the tensor expressions of frequency-dependent permittivity and permeability and discussed influences of the resonant cell structures on waveguiding characteristics. Numerical results show that the slab waveguide loaded with anisotropic metamaterials may, to some extent, behave as the slab waveguides of isotropic left-handed metamaterials (LHMs) core and conventional right-handed materials core. To one’s interest, some unusual properties are revealed in this paper, such as the coexistence of the fundamental guided mode and negative group velocity, and extraordinarily large normal or anomalous group velocity dispersion. Our results may find some potential applications in both linear and nonlinear optical technology.     

光波在左右手系材料界面处的传输特性

根据电磁场理论推导了左、右手系材料界面处菲涅耳公式及菲涅耳系数的角度表达形式,研究了界面处反射系数和透射系数的变化情况,以及布鲁斯特角的确定和全反射时的光学特性,作为进一步研究左手系的特性和相关光学薄膜器件设计的理论基础.     

ABCD matrix formalism for propagation of Gaussian beam through left-handed material slab system

We apply a simple ABCD matrix formalism to investigate beam propagation in left-handed material (LHM) slab systems. Firstly, we derive the expressions for the matrix elements for a single LHM slab. Based on the ABCD matrix, we obtain the field distributions both inside and outside the LHM slab, and the conditions for focusing and phase compensation of the Gaussian beam. Secondly, the derived ABCD law is applied to analyze the propagation properties of Gaussian beams through various cascaded LHM slab systems. The corresponding focusing and phase compensation conditions of the Gaussian beam are also obtained. Our theoretic formalism may be applied as a compact and effective tool for the research of light beam propagation in complex LHM slab systems, since it avoids the complicated integral operation.     

不同厚度有耗左手材料板中的电磁波研究

 基于有损耗的Lorentz模型的时域有限差分（FDTD）方法，模拟了有耗左手材料（LHM）平板对波源的图像聚焦特性。分别计算了不同宽度的左手材料平板结构。通过比较说明电磁波在不同厚度左手材料板中传播方式相同。材料板越薄，其聚焦点的位置越往板边缘靠近。当左手材料板的厚度不满足聚焦尺寸时，该聚焦点将会消失。     

Finite-size effects of a left-handed material slab on the image quality

The characteristics of an imaging system formed by a left-handed material (LHM) slab of finite length are studied, and the influence of the finite length of the slab on the image quality is analyzed. Unusual phenomena such as surface bright spots and negative energy stream at the image side are observed and explained as the cavity effects of surface plasmons excited by the evanescent components of the incident field. For a thin LHM slab, the cavity effects are found rather sensitive to the length of the slab; the bright spots on the bottom surface of the slab may stretch to the image plane and degrade the image quality.     

Evanescent waves of an annular left-handed material lens

The imaging system formed by an annular left-handed material （LHM） lens as well as the evanescent waves in the lens are simulated numerically with a finite-difference time-domain （FDTD） method. For b - a 〉 λ （a and b are respectively the inner and outer radii of the annular lens, and λ is the wavelength）, when a point source is placed at an internal grid point, we demonstrate that the evanescent waves are produced around the internal interface, and cannot propagate outwards. As for b - a 〈λ ）,, the evanescent waves appear around both the internal and the external interfaces, which remarkably implies the coupling between the two interfaces. Hence it can be inferred that the evanescent waves around the external interface participating in the super-resolution imaging result from the coupling of the evanescent waves around the interface. Moreover, the partly uncomprehended properties of the evanescent waves in the LHM slab are also disclosed. It is conducive to understanding the evanescent waves in the LHMs further.     

零平均折射率带隙中离散模的实验研究

通过实验研究了零平均折射率带隙中离散模的传输特性.零平均折射率带隙存在于左手材料与右手材料交替形成的一维光晶体中.在实验中,左手材料与右手材料分别由左/右手复合传输线和右手复合传输线实现.实验结果表明,左手材料与右手材料的色散特性使离散模并没有按照理论上期待的"单点频"传输,而是彻底地覆盖了零平均折射率带隙.由于左手材料在本质上是色散的,因此该实验结论普遍适用于零平均折射率带隙中的离散模,即离散模的出现会使零平均折射率带隙消失.     

The anomalous radiation force of light on a left-handed material

This paper derives the force of the electromagnetic radiation on left-handed materials (LHMs) by a direct applica-tion of the Lorentz law of classical electrodynamics.The expressions of radiation force are given for TE-polarised and TM-polarised fields.The numerical results demonstrate that electromagnetic waves exert an inverse lateral radiation force on each edge of the beams,that is,the lateral pressure is expansive for TE-polarised beams and compressive for TM-polarised beams.The investigation of the radiation force will provide insights into the fundamental properties of LHMs and will provide to better understanding of the interaction of light with LHMs.     

Propagation properties of the chirped Airy vortex beams through left-handed and right-handed material slabs

We present an investigation on the propagation properties of the chirped Airy vortex(CAi V) beams through slabs of left-handed materials(LHMs) and right-handed materials(RHMs). We discuss the influence of chirped parameter C on the propagation of the CAi V beams through LHM and RHM slabs. Our simulation results show that a maximum accelerated velocity appears during the propagation process. The intensity concentration of the CAi V beams increases with the absolute value of the chirped parameter. The peak intensity of the CAi V beams changes abruptly, and the chirped parameter plays an active role on the difference of the maximum and the minimum. In the energy flow, we find that the effects of the chirped parameter on the strength of the vortex are different at different propagation distances.     

Superpositions of Laguerre-Gaussian Beams in Strongly Nonlocal Left-handed Materials

We present beam solutions of the strongly nonlocal nonlinear Schrödinger equation in left-handed materials (LHMs). Different Laguerre-Gaussian (LG) necklace beams, such as symmetric and asymmetric single layer and multilayernecklace beams are created by the superposition of two single beams with different topological charges. Such superpositions are then propagated through LHMs, displaying linear diffraction. It is found that the superposition of two LG_nm beams with opposite topological charges does not show rotational behavior and that there exists rotation for other topological charge combinations. Our theory predicts that the accessible solitons cannot exist in LHMs.     

A candidate three-dimensional GHz left-handed metamaterial composed of coplanar magnetic and electric resonators

GHz left-handed metamaterials (LHMs) composed of coplanar magnetic and electric resonators were proposed in this paper. On each of the unit cells, the electric resonator is placed in the center space of the magnetic resonator. By adjusting the geometrical dimensions of the resonators, negative magnetic response of the magnetic resonator and negative electric response of the electric resonator can be tuned to be coexistent at the same frequencies. The effective constitutive parameters were retrieved. The results verified simultaneous negative permeability and permittivity as well as negative index of the proposed LHMs. Based on the above work, two- and three-dimensional LHMs that make use of coplanar magnetic and electric resonators were proposed. The work done in this paper is of great reference values in fabricating three-dimensional LHMs.     

Spin moments of particles detected using the spin Hall effect of light through weak quantum measurements

Here it is shown that magnetic materials with either microscopic atomic or molecular moments or macroscopic nanoscopic moments, represented by macroscopic permeability, can be detected by the quantum spin Hall effect of light (QSHEL), showing “spin” displacements normal to the interface with greater richness than previously found for dielectric materials. Also, it is proven for isotropic left-handed materials (LHMs), which rely upon magnetic action, that they do not display altered QSHEL results compared to their right-handed material (RHM) cousins which do.     

左手介质矩形波导导模和表面模的场分布

从麦克斯韦方程组出发,结合电磁场的边界条件,推导出介质矩形波导导模的一般色散方程.对普通介质矩形波导和左手介质矩形波导的导模场分布分别进行了数值模拟.通过对比两种介质矩形波导的导模场分布的模拟结果,发现左手介质矩形波导Ex22模的场分布比普通介质波导Ex00模的场更集中在波导中部.同时,根据处理普通介质矩形波导的Marcatili方法.类比得到左手介质矩形波导表面模的色散方程,并数值模拟了低阶模的场分布,结果表明,能量主要集中在波导的四个角区以及波导的边缘.     

非线性左手材料的时域研究

 分析了非线性左手材料模型，推导了非线性左手材料中的时域有限差分法及完美匹配层的计算式。数值模拟了具有Kerr非线性效应的左手材料平板中的电磁波。观察到该材料同样具有电磁聚焦特性。对比线性左手材料，其聚焦点的幅度和位置都会发生偏移。同时改变波源的强度及其到平板边界距离，讨论了不同距离情况下该非线性左手材料平板对电磁波分布的影响。当波源距离材料平板足够远，通过非线性左手材料聚焦的电场强度几乎集中在其外表面。     

不对称左手介质平板波导模式特性分析

对不对称左手介质平板波导的几个低阶的TE模和TM模进行了数值计算,得到了模式特征方程,分析了归一化传播常数β/k_0随平板厚度d变化的色散关系,作出了模式的电场E_y(x)分布．在左手介质平板波导中,每一模式都有截止点, TE_0模和TM_0模不出现,在我们给出的特定的介质参数下,TE_1模和TM_1模不能和其他高阶模式共存,其归一化传播常数β/ k_0随k_0d的增加而减小．给出的结果对左手介质元器件的研究有实际的参考意义．