Analysis of Circular Dielectric Waveguide with Chiral Cladding

The propagation characteristics of a circular dielectric waveguide with chiral media filled in the cladding are investigated. The relation between the cutoff frequency and the chiral admittance, the dispersion curves for some modes with different angular mode numbers and the transverse distribution of fields are presented. Some new features different from the ordinary circular dielectric waveguide are resulted. The results show that the cladding chirality may lead to a single-mode operation in the circular dielectric waveguide.     

Guided and surface modes in chiral nihility fiber

Guided and surface modes in the chiral nihility fiber consisting of a chiral nihility metamaterial core with an achiral cladding have been investigated. The dispersion equations of guided and surface modes in the chiral nihility fiber and their cutoff frequencies are derived. Dispersion curves of guided and surface modes are presented and the effect of chirality parameter on dispersion curves is discussed in detail. Some novel propagation characteristics are found.     

金属包层对称平面单轴晶体波导的模式场(Ⅱ)

对于晶体光轴平行于波导界面的结构,讨论了光在金属包层对称平面单轴晶体波导(波导层是单轴晶体,两个波导界面均为金属)内的传输特性.解析地得到了这种结构下波导模式场的精确解.模式场的性质因单轴晶体的性质不同而异.对于正单轴晶体,波导的主模是横电波,任何频率的光波均可激励该模式;当频率满足一定条件时,波导内传输单模,否则,将激励起高阶模式.高阶模既非TE波,也非TM波,而是两者耦合而成的混合模.对于负单轴晶体,波导的主模是一种混合模,该模式同样可被任何频率的光波所激励;当频率满足一定条件时,波导内传输单模,否则 关键词： 平面金属波导 单轴晶体 模式场 混合模     

零折射率手征包层光纤中导模的奇异特性

 对零折射率手征介质（介电常量和磁导率同时等于零的手征介质）作为包层的光纤中模式的奇异特性进行了理论研究.给出了导模的电磁场分布公式,推导出导模色散方程和功率的数学表达式,通过数值计算,给出了不同手征参量情形下的色散曲线,讨论了手征参量对归一化功率的影响,发现了导模的一些奇异特性,如存在表面波模、基模单模区,出现传播常量双值、模式交叉、功率储存现象等,特别是出现了纤芯和包层中的功率都为负值的完全后向波奇异模式.     

Analysis of a Metal-Coated Planar Dielectric Waveguide with Chiral Cladding

The propagation characteristics of a metal-coated planar waveguide with chiral media filled in the cladding are presented. The effects of chirality on cutoff, dispersion characteristics and field distributions of the waveguide are studied. The results show that cladding chirality brings phase chopping to the transverse electric field component of those modes with odd mode numbers.     

Guided modes in chiroplasma-filled perfect electromagnetic conductor parallel-plate waveguides

Theoretical analysis of electromagnetic wave propagation in a perfect electromagnetic conductor (PEMC) parallel-plate waveguide filled with a chiroplasma material is presented in this article. The derived formulations are general and can analyze perfect electric, perfect magnetic, or PEMC waveguides filled with any general isotropic/anisotropic material including plasma and metamaterials. The characteristic equation for the modes in this waveguide is obtained, and the behavior of the dispersion curves and the energy flux are examined and evaluated numerically. The results demonstrate that the chirality parameter, the plasma frequency, and the cyclotron frequency influence the behavior of the energy flux transported in the guide, in magnitude and orientation. The bifurcated mode cutoff frequencies are sensitive to the variations in the filling material parameters and likewise effected by the variations in the PEMC walls admittance parameter.     

Anomalous dispersion and group velocity properties in subwavelength uniaxial metamaterial waveguide with metal cladding

We investigate propagation behavior of electromagnetic waves in a slab uniaxial metamaterial waveguide with metal cladding and discuss the dispersion relation, group velocity and energy flux distribution of transverse electric guided modes in two kinds of uniaxial metamaterial waveguides with different orientations of optical axis in detail. The numerical results show that there exist anomalous dispersion properties such as backward modes existing in low-frequency range, and the group velocity can be negative or approach zero. If the orientation of optical axis is selected properly, each guided mode has two dispersion curves—one is normal dispersion and another belongs to anomalous dispersion and shows a transition from a backward mode to a forward one with the angular frequency increasing. In addition, the condition of the existence of cutoff frequency is clarified. These properties may have potential applications in optical information storage, optical communication, integrated optics and nanophotonic devices.     

Surface plasmon propagation in a metal strip waveguide with biaxial substrate

Surface plasmon propagation in a nano metal strip waveguide with a biaxial substrate material was studied. The dispersion of the four fundamental modes propagating in the strip waveguide structure was analysed using a formalism based on the method of lines. The propagation properties of these modes with respect to the thickness of the metal film was studied, with two different biaxial materials as substrate for the waveguide. The results were then compared with the asymmetric strip waveguide structures with isotropic substrate and a uniaxial anisotropic substrate. Propagation characteristics as a function of longitudinal and transverse anisotropic components of the substrate material were also studied. The characteristics of the fundamental modes are observed to vary depending on the anisotropy of the biaxial material used.     

手征参数对光纤中模式特性的影响

对圆芯和包层都是手征介质的阶跃型手征光纤进行了解析求解，导出了模式特征方程，给出了手征光纤中模式场，光强和光功率分布的表达式。分别研究了纤芯和包层中的手征参数对模式特性的影响．。     

Effect of plasma on modal dispersion characteristics of elliptical Bragg waveguide

In this paper, the dispersion characteristics of a plasma filled elliptical Bragg waveguide is investigated. The modal characteristic equations of the proposed Bragg waveguide for both ω > ω_p and ω < ω_p are derived. The effects of plasma frequency, numbers of cladding layers and the eccentricity of elliptical Bragg waveguide on the dispersion characteristics are studied. The analysis shows that the introduction of plasma in the proposed waveguide allows to control the propagation of modes.     

双包层手性光纤中导模的光功率特性

在对W型阶跃双包层手性光纤进行解析求解的基础上,对几个低阶导模的功率特性进行了仔细的研究.对典型的内包层厚度,计算了几个低阶模留在纤芯中的光功率随纤芯和内外包层的手性参数的变化关系曲线,讨论了纤芯和内外包层的手性参量以及内包层厚度对不同符号模式的功率特性的影响.内包层厚度越大,功率越被限制在纤芯中.随着纤芯中手性参量的增大, HE－11模和HE－21模（HE01模）限制在纤芯中的光功率缓慢增加,而HE11模和HE21模（HE02模）限制在纤芯中的光功率则逐渐减小.包层手性参量的作用正好与此相反.     

Analysis of Planar Dielectric Waveguide with Chiral Cladding

The propagation characteristics of a planar waveguide with chiral media filled in the cladding are presented. The effect of chirality on cutoff, dispersion and field distribution of the waveguide are studied. The results show that the cladding chirality may lead to a single-mode operation in the planar waveguide.     

单模手征光纤研究

对圆芯和内外包层都为手征介质构成的双包层手征光纤（W型）进行了解求解,导出了模式场解及模式特征方程,然后用数值计算的方法研究了手征参数对模式的色散曲线和截止频率的影响,结果发现在双包层光纤的纤芯中引入手征或在单包层光纤的包层中引入手征,都可以实现单模工作。     

Analysis of Circular Chiral Dielectric Waveguides

The general eigenequations and the field expressions for circular waveguides containing chiral material in both the core and the cladding are given in a simple formulation. The results indicate that there are two types of field distribution which is related to the operating wavelength and chiral admittance. When the chiral admittance is larger than a critical value, the fields of one kind of circularly polarized wave in the core become exponentially-like damping in the transverse direction. Based on the eigenequations, the characteristics of a circular waveguide with chiral medium filled in the core are investigated. The relation between the cutoff frequency and the chiral admittance, the dispersion curves for some modes with different angular mode number and the transverse distribution of fields are presented. Some features different from the ordinary circular waveguide are resulted.     

High-Frequency Backward Waves in Longitudinally Magnetized Gyrotropic Waveguides

Backward waves in waveguides completely filled with magnetoactive plasma (gaseous or semiconductor plasma) have been investigated numerically. It is shown that two types of backward waves exist in such waveguides: cyclotron backward waves and waveguide HE-modes. While the cyclotron modes are backward waves at arbitrary system parameters (plasma density, magnetic field and waveguide radius), the waveguide backward waves appear only at certain values of there parameters. In addition the cyclotron backward waves can propagate at arbitrary wave-number k_z and at arbitrary phase velocity. The backward waveguide modes exist only at limited values of k_z and of phase velocities.     

Optical guided dispersions and subwavelength transmissions in dispersive plasmonic circular holes

The light transmission through a dispersive plasmonic circular hole is numerically investigated with an emphasis on its subwavelength guidance. For a better understanding of the effect of the hole diameter on the guided dispersion characteristics, the guided modes, including both the surface plasmon polariton mode and the circular waveguide mode, are studied for several hole diameters, especially when the metal cladding has a plasmonic frequency dependency. A brief comparison is also made with the guided dispersion characteristics of a dispersive plasmonic gap [K.Y. Kim, et al., Opt. Express 14, 320–330 (2006)], which is a planar version of the present structure, and a circular waveguide with perfect electric conductor cladding. Finally, the modal behaviour of the first three TM-like principal modes with varied hole diameters is examined for the same operating mode.     

Light transmission along a slab waveguide with a core of anisotropic metamaterial

We investigated the dispersion property of a slab waveguide with an anisotropic metamaterial core whose permittivity tensor is partially negative. The subwavelength guidance characteristics are presented based on the boundary conditions. The results show that, at some specific frequencies, many high-order modes can exist in present waveguide even with the thickness of the guiding core 10 times smaller than the working wavelength. It is also found that different orientations of the optical axis of the anisotropic core will lead to different dispersion of the guided modes. If the orientation of the optical axis is properly chosen, the guided modes show a transition from backward wave to a forward wave as the frequency increases. During this transition, the group velocity of some guided modes can approach zero. Since the anisotropic metamaterial we discuss here can be fabricated in GHz, near- and mid-infra-red frequencies, our result may find some applications in wave trapper, integrated optical and nanophotonic devices.     

包层为负折射率介质的抛物型渐变光纤色散特性分析

研究了纤芯为各向同性非均匀材料,而包层为负折射率均匀介质光纤的色散特性.在纤芯满足弱渐变条件的假定下,按矢量场分析法,通过芯层与包层的介电常数比ξ和磁导率比η,讨论了导波模式色散特性对左手介质包层材料的依赖性.分析表明,ξ和 η对轴对称模色散曲线的低频段影响较大,但对非轴对称模影响不大.ξ和 η对导波模式的截止频率没有影响.由于该光纤中的HEm1模的截止频率都等于0,所以不存在理论上的单模区,但仍可近似实现无色散传输.     

Surface polaritons in planar chiral nihility meta-material waveguides

Chiral nihility meta-material is a special case of chiral medium, in which both the permittivity and permeability are equal to zero. The feature of surface wave modes (or surface polaritons) in the planar chiral nihility waveguides which the core or cladding consist of chiral nihility meta-materials is investigated. The dispersion curves, electromagnetic fields, energy flow distribution and the power of surface wave modes in the planar chiral nihility waveguides are presented for typical parameters. Some novel peculiarities such as anomalous dispersion curves, the power flows opposite to the wave vector propagation direction in the planar chiral nihility waveguides have been found.