左手材料和负折射率

对于左手材料折射率的符号取法做了详细的分析,给出了n=εμ的来源.     

Energy flow in negative index materials

From Maxwell's equations, we compute the speed and the direction of propagation of active power refractedfrom air into a negative index material. We prove, both analytically and numerically that the power mayrefract positively even if phase fronts refract negatively. Considerations on the usage of ray optics inproblems involving negative index materials are drawn.     

负折射率介质测试装置设计与测试

为深人了解负折射率媒质的奇异传输特性,基于斯涅耳折射原理,设计并加工了一种用于测试X波段((8.2-12.4GHz),以亚铁磁材料为基体,内嵌金属线阵列宏结构的负折射率介质样品折射特性的实验装置.分别测试了楔形石蜡样品和楔形负折射率介质样品在波段的折射特性,对石蜡样品测试结果的分析证明了该折射特性测试装置的有效性,对负...     

负折射率介质测试装置设计与测试

为深入了解负折射率媒质的奇异传输特性,基于斯涅耳折射原理,设计并加工了一种用于测试X波段（8.2~12.4 GHz）,以亚铁磁材料为基体,内嵌金属线阵列宏结构的负折射率介质样品折射特性的实验装置。分别测试了楔形石蜡样品和楔形负折射率介质样品在X波段的折射特性,对石蜡样品测试结果的分析证明了该折射特性测试装置的有效性,对负折射率介质样品测试结果的分析证明了合成介质确实具有负折射效应。通过电磁仿真方法,测试了平行板负折射率介质的波束位移特性,进一步证明了该种合成介质的负折射特性。     

Imaging properties of uniaxially anisotropic negative refractive index materials

The imaging properties of uniaxially anisotropic negative refractive index materials have been investigated theoretically. Based on an accurate theoretical formulation, we have discussed in detail whether and under what conditions the slabs of uniaxially anisotropic negative refractive index materials will have the power to focus perfectly all Fourier components of an image. It was shown that if the effects of absorption and dispersion can be neglected, under some particular conditions the slabs of uniaxially anisotropic negative refractive index materials will have the power to focus perfectly all E-mode or all H-mode or both E- and H-mode Fourier components of an image. It was also shown that perfect focus cannot occur in the presence of absorption and dispersion, but if the effects of absorption and dispersion are rather small, excellent focus can still occur.     

负媒质模型的时域有限差分法分析

负折射率媒质是一种人造媒质,在某一微波波段内其介电常数和磁导率同时为负值。对TE模电磁场满足的麦克斯韦方程组进行数值处理,解决了直接利用时域有限差分方法在Yee’s网格下计算负折射率媒质内部场分布时的数值发散问题。通过数值算例,验证了方法的可行性,模拟了负折射率媒质内部及周围的电磁场分布。     

负媒质模型的时域有限差分法分析

 负折射率媒质是一种人造媒质,在某一微波波段内其介电常数和磁导率同时为负值。对TE模电磁场满足的麦克斯韦方程组进行数值处理,解决了直接利用时域有限差分方法在Yee’s网格下计算负折射率媒质内部场分布时的数值发散问题。通过数值算例,验证了方法的可行性,模拟了负折射率媒质内部及周围的电磁场分布。     

负折射率材料对产生Casimir排斥力的影响

研究了负折射率材料对产生Casimir排斥效应的影响. 两材料板间的Casimir排斥力的发生取决于两板以及其间媒质的电磁特性,通过理论与数值结果的分析研究给出电磁特性所影响排斥力的产生趋势. 对于由Drude-Lorentz型色散关系描述等效介电常数和磁导率的负折射率材料,调节各特征频率参数可实现Casimir排斥效应. 关键词： Casimir排斥力 负折射率材料 Drude-Lorentz型色散关系     

Extreme damping in composite materials with a negative stiffness phase

Composites with negative stiffness inclusions in a viscoelastic matrix are shown to have higher stiffness and mechanical damping tandelta than that of either constituent and exceeding conventional bounds. The causal mechanism is a greater deformation in and near the inclusions than the composite as a whole. Though a block of negative stiffness is unstable, negative stiffness inclusions in a composite can be stabilized by the surrounding matrix. Such inclusions may be made from single domains of ferroelastic material below its phase transition temperature or from prebuckled lumped elements.     

Propagation of p-polarized waves in a linearly graded index film surrounded by negative index materials

The theory of step-index waveguides is well-established. Most practical slab waveguide structures have a graded-index profile. The basic properties of graded-index planar waveguide structures are similar to those of step-index waveguides with subtle differences. The most common types of graded-index slab waveguides are linearly and exponentially graded-index profiles. We here treat linearly graded-index slab waveguide. In this work, a three-layer waveguide structure with linearly graded-index film is considered. We assume three structures: the first structure comprises a left-handed material (LHM) cladding, the second structure contains a LHM substrate layer and the third has a LHM cladding and substrate. Closed-form expressions for electric and magnetic fields and the characteristic equation are derived. The three normalized parameters: the asymmetry coefficient (a), the normalized film thickness (V) and the normalized guide index (b) are used to study the dispersion properties of the proposed slab waveguide structure.     

Elastic composite materials having a negative stiffness phase can be stable

We prove that composite materials containing an isotropic phase having negative bulk and Young's moduli (hence being unstable by itself) can be stable overall, under merely applied traction boundary conditions, if the stable encapsulating phase is sufficiently stiff. We derive specific quantitative requirements on the elastic moduli of the constituent materials that ensure composite stability for two fundamental composite geometries. These results legitimize the concept of negative-stiffness-phase composites, thus dramatically expanding the parameter landscape in which novel and optimal overall material properties may be sought.     

Photonic band gap from a stack of positive and negative index materials

Layered heterostructures combining ordinary and negative refractive index materials are shown to display a new type of photonic band gap corresponding to zero (volume) averaged refractive index. Distinct from band gaps induced by Bragg scattering, the zero-n; gap is invariant upon a change of scale length and is insensitive to disorder that is symmetric in the random variable. A metallic structure that exhibits such a band gap is explicitly designed, and its properties are calculated with accurate finite difference time domain simulations.     

Non-Bragg bandgaps of quasi-one-dimensional comb-like structures composed of positive and negative index materials

Quasi-one-dimensional comb-like periodic and aperiodic structures composed of positive index materials branch resonators and negative index materials backbone waveguide are physically fabricated by using transmission line approach. It is theoretically shown that the structures possess a non-Bragg band-gap which is invariant with a change of scale length and robust against disorder. The gap edges are determined by zero average permittivity of the branch and the backbone and zero permeability of the backbone materials, respectively. The transmission properties of the structures are investigated by changing the (average) resonator size d_Band the resonator spacing d_Arespectively. The experimental results agree well with the theoretical predictions and numerical simulations, which demonstrate the independence of the special gap on the scaling and disorder in the structures.     

负折射率媒质雷达散射特性分析

 从负折射率媒质的本构关系出发,应用分段线性递推卷积(PLRC)方法推导出负折射率媒质中的时域有限差分（FDTD）计算公式,建立了基于分段线性递推卷积的FDTD方法(PLRC-FDTD)。并应用该方法计算了负折射率媒质覆盖导体柱的雷达散射截面,分析了负折射率媒质参数对其雷达散射截面的影响。结果表明,恰当地选择负折射率媒质参数能有效减小目标的雷达散射截面。     

负折射率媒质雷达散射特性分析

从负折射率媒质的本构关系出发,应用分段线性递推卷积(PLRC)方法推导出负折射率媒质中的时域有限差分（FDTD）计算公式,建立了基于分段线性递推卷积的FDTD方法(PLRC-FDTD)。并应用该方法计算了负折射率媒质覆盖导体柱的雷达散射截面,分析了负折射率媒质参数对其雷达散射截面的影响。结果表明,恰当地选择负折射率媒质参数能有效减小目标的雷达散射截面。     

Resonant modes and inter-well coupling in photonic quantum well with negative index materials

The transfer matrix method was used to study the resonant modes in photonic quantum well by stacking different photonic crystals consisting of positive index materials and negative index materials. The eigenfrequency equation for the resonant modes is derived. It is found that these resonant modes are omnidirectional, and the number of resonant modes is equal to the period number of photonic quantum wells. Moreover, the resonant modes become N-fold splitting in the N photonic quantum wells. The splitting intervals increase with the deceasing of photonic barrier thickness due to the coupling among the wells.     

Narrow transmission bands of quasi-1D comb-like photonic waveguides containing negative index materials

Using the interface response theory, we investigate the band structure and transmission of quasi-1D comb-like photonic waveguides with side branches composed of negative index materials. Numerical results exhibit the existence of discrete modes in band structure. These discrete modes are corresponding to narrow transmission bands which separated by large forbidden band in the transmission spectrum. Meanwhile it is shown that the narrow transmission bands become narrower with the increase of the number of side branches. The above properties are still maintained when the negative index materials are dispersive and lossy.     

负折射率材料单球面近轴成像奇特规律的研究

研究了负折射率(n′<0)材料单球面折射对近轴光线的成像规律.理论推导证实负折射率材料单球面近轴成像的所有公式与我们所熟悉的常规材料(n′>0)单球面的完全相同,但由于n′<0,它的成像规律完全不同于常规材料的.文中通过物距-像距曲线比较了两种材料的物-像关系,并对(n′<0,f′>0,f>0)情形下的物像位置、虚实正倒、缩放规律等进行阐述,给出了物像空间的对应图示.     

Form birefringence and negative index change created by femtosecond direct writing in transparent materials

Although femtosecond lasers have proved to be of great utility for micromachining within bulk transparent materials, little is known about the fundamental physics that drive the process. Depending on the laser intensity delivered to the sample, any of three types of feature can be written into the glass. We observed that in the intermediate regime there is a correlation among the negative sign of the effective index change, the presence of anisotropic reflection, and birefringence. We propose a model that can explain all three principal characteristics. Results show that the local index change can be as high as 10(-1).