Paraxial propagation of cosh-Airy vortex beams in chiral medium

Propagation dynamics of the cosh-Airy vortex(CAiV) beams in a chiral medium is investigated analytically with Huygens–Fresnel diffraction integral formula. The results show that the CAiV beams are split into the left circularly polarized vortex(LCPV) beams and the right circularly polarized vortex(RCPV) beams with different propagation trajectories in the chiral medium. We mainly investigate the effect of the cosh parameter on the propagation process of the CAiV beams.The propagation characteristics, including intensity distribution, propagation trajectory, peak intensity, main lobe's intensity, Poynting vector, and angular momentum are discussed in detail. We find that the cosh parameter affects the intensity distribution of the CAiV beams but not its propagation trajectory. As the cosh parameter increases, the distribution areas of the LCPV and RCPV beams become wider, and the side lobe's intensity and peak intensity become larger. Besides, the main lobe's intensity of the LCPV and RCPV beams increase with the increase of the cosh parameter at a farther propagation distance, which is confirmed by the variation trend of the Poynting vector. It is significant that we can vary the cosh parameter to control the intensity distribution, main lobe's intensity, and peak intensity of the CAiV beams without changing the propagation trajectory. Our results may provide some support for applications of the CAiV beams in optical micromanipulation.

Focal region field of a two dimensional Gregorian system coated with isotropic Chiral medium

Focal region field of a two dimensional Gregorian system coated with chiral medium is analyzed at high frequency. Maslov's method is used because the Geometrical Optics approximation fails at focal points. Maslov’s method combines the simplicity of ray theory and the generality of Fourier transform. Fields patterns are calculated numerically and the results are plotted. The effects of thickness of chiral layer, chirality parameter of the chiral medium and permittivity of the medium are analyzed. The problem of simple dielectric layer is discussed as a special case of this problem.

基于手征原子媒质的光学时域隐身调控

基于五能级结构手征原子媒质,对光学时域隐身在外场调控下的实现进行了研究。在该五能级手征原子系统下,推导了原子媒质与光场参数相关的等效电磁响应参数的广义表达式,进而根据群折射率计算输出光脉冲。数值计算了五能级原子系统的外场以及原子媒质相关参数对隐身时域窗口大小以及形成时域窗口的光脉冲强度的影响。结果表明,时域窗口大小随控制场Rabi频率改变但基本不依赖于控制场的相位变化;两个耦合场相位在一个周期内的变化对左右旋圆极化输出波特性影响相反;两个耦合场中,当其中一个耦合场的Rabi频率减小时,对应时域窗口增大,但同时也会使形成窗口的脉冲强度减弱,而另一个耦合场Rabi频率则对时域窗口的大小影响较小。因此改变控制场和两个耦合场的强度、相位和失谐等参量可有效地调控输出脉冲的加速和延迟,产生显著的隐身时域窗口,提供了一种可操控的光学时域隐身的方案。

用MEI—FD方法分析Chiral媒质的电磁散射问题

本文应用不变性测试分程和有限差分方法分析Ｃｈｉｒａｌ媒质的电磁散射问题。应用该方法时，要在所讨论的区域内建立起一组有关电场和磁场的耦合差分方程，并且要在截断边界上应用不变性测试方程建立起有关边界点系数的方程。文中给出了一些非均匀。

SPLITTING OF THE SPECTRAL DOMAIN ELECTRICAL DYADIC GREEN’S FUNCTION IN CHIRAL MEDIA

A new method of formulating dyadic (Green's) functions in lossless,reciprocal and unbounded chiral medium was presented.Based on Helmholtz theorem and the non-divergence and irrotational splitting of dyadic Dirac delta-function was this method, the electrical vector dyadic (Green's) function equation was first decomposed into the non-divergence electrical vector dyadic (Green's) function equation and irrotational electrical vector dyadic (Green's) function equation,and then (Fourier's) transformation was used to derive the expressions of the non-divergence and irrotational component of the spectral domain electrical dyadic (Green's) function in chiral media.It can avoid having to use the wavefield decomposition method and dyadic (Green's) function eigenfunction expansion technique that this method is used to derive the dyadic (Green's) functions in chiral media.

Polarization characteristics of chiral photonic crystal fibers with an elliptical hollow core

The theoretical study of dielectric-chiral photonic crystal fiber （PCF） with an elliptical hollow core is presented. The band structure of chiral photonic crystal （PhC） is calculated by using a modified plane-wave expansion （PWE） method. By examining the out-of-plane photonic bandgaps （PBGs） of chiral PhC, a kind of chiral PCF with a hollow core is designed and their eigenstates are calculated. The distributions of mode field and polarization state are demonstrated, and how the structural asymmetry of the core together with the chirality in the background affects the modal polarization is discussed. The dependences of birefringence on chirality for different ellipticities of core are investigated.

The Study of Electromagnetic Scattering by a Non-perfectly Conductor in Chiral Media by Potential Theory

This paper is concerned with the electromagnetic scattering by a nonperfectly conductor obstacle in chiral environment. A two-dimensional mathematical model is established. The existence and uniqueness of the problem are discussed by potential theory.

ELECTROMAGNETIC SCATTERING BY A PERFECTLY CONDUCTING GRATING IN A HOMOGENEOUS CHIRAL ENVIRONMENT

The scattering of plane time-harmonic electromagnetic waves propagating in a homogeneous chiral environment by a perfectly conducting grating is studied.The problem is simplified to a two-dimensional scattering problem,and the existence and uniqueness of solutions are discussed by an integral equation approach.

MULTI-MODE NETWORK ANALYSIS FOR DISCONTINUITIES IN PARALLEL-PLATE WAVEGUIDES PARTIALLY FILLED WITH MULTI CHIRAL RODS

The reflection and transmission characteristics of the guided modes in parallel-plate waveguides partially filled with one or multi chiral rods have been investigated by a method, which combines the multi- mode network theory with a rigorous mode matching procedure. The formulas of the reflection and transmis- sion coefficient matrix are derived. The numerical results for different cases are presented and have indicated that the chirality parameters and the geometrical dimensions of the chiral rods have significant influence on the reflection and transmission characteristics of the guided modes.

Chiral媒质的研究进展及其应用

本文对 Chiral 媒质的本构方程和一般电磁场理论进行了概括。详细阐述了有关Chiral 媒质的电磁学研究进展的四方面,即波导问题、辐射问题,散射问题和不均匀媒质中的传播问题。最后对 Chiral 媒质的应用前景及其有待解决的工程问题进行了简述。

THE COMBINED EFFECTS OF GYROTROPY AND CHIRALITY IN CIRCULAR FARADAY CHIROWAVEGUIDES

Based on the method of separating variables and the technique of Muller’s calculating roots, the propagation characteristics of hybrid modes in homogeneous and inhomogeneous circular Faraday chirowaveguides are examined in detail. Numerical results are presented to demonstrate the combined effects of different constitutive parameters on the mode bifurcation, symmetry and nonreciprocity, backward-wave and attenuation of hybrid modes, which are different from the cases of ordinary gyrotropic and reciprocal chiral waveguides.

手性介质中斜入射电磁波散射问题的积分方程法

考虑均匀手性介质中无限长阻抗柱体斜入射电磁散射问题。在某些假设下,该散射问题可以表示为电场和磁场z分量的具有广义斜导数边界条件的二阶椭圆方程组。通过场量分解部分解耦以及位势理论,将该散射问题转化为两个积分方程组。与电磁波垂直入射情形不同,该积分方程组不是通常的第二类Fredholm算子方程形式,因为该方程组中含有单层势的切向导数。说明了该算子是指标为0的Fredholm算子。利用Fredholm理论,证明了边界积分方程解的存在唯一性,并给出了一种求解该积分方程的数值方法。

手征媒质涂层参数对反射系数的影响

对手征媒质单涂层的反射系数受其电磁特性参数ε、μ、ζ和涂层厚度ｄ 的影响进行了计算机模拟分析。分析表明，手征媒质的旋波参量并不总是对涂层的吸波特性起着改善的作用；当手征媒质的归一化旋波参量ζｒ ＝ １ 时，材料吸波特性最好。计算表明，当涂层厚度增加到一定厚度后，其反射系数几乎与厚度无关，此厚度随涂层材料的电磁特性参数不同而改变。手征媒质的介电率。

手征平板介质波导中的场分析

本文首次研究了手征平板介质波导中电磁波的传播特性,给出了波导中的场分布、色散关系和截止方程,以及最低截止波数Kc随手征导纳ζc的变化规律。结论表明,在手征平板介质波导中,TE、TM和TEM模均不能单独传输,其伸输模是耦合模。当ζc趋于零时,本文的所有结果均退化成通常平板介质波导情形。

毛细管电泳柠檬酸-Zn^(2+)体系对异亮氨酸对映体的手性分离

应用毛细管电泳/电容耦合非接触式电导(CE-C4D)分离检测技术,研究了柠檬酸-Zn^(2+)体系对异亮氨酸对映体的手性识别行为。结果表明,采用未涂层石英毛细管(45 cm×50μm,Leff=40 cm),以2.8 mmol/L NaOH+0.8mmol/L柠檬酸+2.0 mmol/L乙酸锌为非手性介质电泳运行液,分离电压+13 kV,D,L-异亮氨酸对映体得到了良好的手性识别,对映体分离度达到2.0。线性检测范围为1.0~20 mg/L,检出限(S/N=3)为0.40 mg/L。对影响分离度的因素(Zn^(2+)的浓度、电泳运行液的组成、分离电压以及其他氨基酸的干扰情况等)进行了详细的讨论,并对手性识别机理作了初步探讨。

多层旋波媒质平板的反射与透射

本文先利用电磁场的边界条件导出平面电磁波垂直入射于多层平板旋波媒质的透射场表达式。然后用传输线理论中的阻抗法，解决了多层平板旋波媒质的反射问题。最后对多层旋波媒质平板的一特例－双层结构型旅波吸波材料进行了计算机辅助设计分析，分析表明，双层代替单层可以在一定程度上改善涂层的吸波特性。

手征材料涂覆导体目标电磁散射特性的PO分析

从Maxwell方程出发 ,推导出平面波照射下手征介质涂覆导体目标表面等效电磁流的一般表达式 ,并基于切平面近似 ,给出了计算手征介质涂覆导体目标电磁散射的物理光学 (PO)解。在此基础上 ,计算了T形结构及锥柱结构的散射特性 ,分析了手征材料参数对电磁散射的影响 ,得到了一些有益的结果。

金属螺旋的旋波特性研究

采用细线近似对金属螺旋线的电磁散射作矩量法数值研究，对于具有镜象对称特性的右旋和左旋金属螺旋，计算了不同尺寸、不同电磁波投射方向下的感应电流和散射场辐值。计算结果表明，由它们产生的感应电流和散射场同样具有镜象对称性。计算得到的前向和背向散射场显示不同族向的螺旋对散射场的极化产生相反的旋转。

电导率对旋波介质吸波性能的影响

旋波介质的吸波性能与介质的手性参量有关,而手性参量又与介质的电导率有关。制备了4种不同电导率基底的旋波介质,根据自由空间测量旋波介质手性参量的方法,通过测量两次复反射系数、透射偏转角和椭偏率,计算得到介质的手性参量和吸波性能。结果表明,改变旋波介质基底的电导率,可以调节旋波介质的电磁性能和吸波性能,当基底的电导率为4.2×10–2 S/cm时,旋波介质的吸波效果最好,其反射系数的最小值达–24 dB。

填充多层互易手征介质金属同轴线传播特性

采用在圆柱坐标系中分离变量的方法,推出填充多层互易手征介质的金属同轴线各层电磁场之间的关系,得到其模式特征方程和圆波导模式特征方程,给出了填充两层手征介质金属同轴线部分模式的色散特性的数值计算结果,分析了手征介质参量及两层手征介质厚度变化等对手征同轴线传播特性的影响。如果互易手征介质的手征参数等于零,可得填充普通介质的同轴线的模式特征方程。与填充普通介质的同轴线中的模式相比,手征同轴线中的模式发生了分叉。当同轴线中所填介质的折射率增大时,其模式归一化截止频率和进行基模单模传输的带宽归一化频率都将减小。