介质波导阵列电磁特性分析

根据已提出的二维周期介质严格理论,比较详细地分析和研究了介质波导阵列的电磁特性．首先,对存在纵向波传播时(kz≠0)的空间谐波相互作用特征进行了分析,得出了横向波传播色散特性．其次,在横向平面上的两互相垂直方向的波数相等(kx=ky)时,对不同波频率下空间谐波相互作用特性及其产生的阻带分布特征作了详细研究,并对横向纵向波传播色散关系进行了分析和计算．最后,得出介质波导阵列存在纯纵向导波的十分有意义的结论,具有实用价值．     

用Marcatili方法分析矩形介质波导阵列

将Marcatili近似分析方法在应用范围和处理方法上进行了一些改进，并之为扩展的Marcatili方法，根据Floquet理论和该方法，分析了矩形介质波导阵列，推得两个一维周期介质结构的耦合特征方程。数值计算结果表明，在微扰的情况下，特征方程所得的结论与其他方法巳取得的结果吻合很好，它们都能较准确地反应出通带、阻带和空间谐波之间的相互作用等主要周期特性。     

介质纤维束波导电磁波传播特性分析

介质纤维束波导是一种圆柱介质波导阵列．根据已建立的二维周期介质理论,对矩形排列的圆柱介质波导阵列进行了数值计算和分析,得出了电磁波在圆柱介质波导阵列中传播的一些特征,并且和矩形介质波导阵列电磁波传播特性作比较,结果较为满意。     

多层圆柱形Chiral介质波导的传播特性

本文利用递推本征函数法分析计算了多层圆柱形chiral介质波导的传播特性。文中推导了不同chiral介质层中电磁场的递推关系,得到了计算N层圆柱形chiral介质波导色散特性的特征方程。作为数值示例,文中给出了几种chiral介质波导传播特性的计算结果。     

K0．3MoO3电子辐照下有序一无序转变及恢复

准一维K0．3MoO3蓝青铜中的电荷密度波(CDW)失稳一直是凝聚态物理研究的热点之一。在180K温度附近K0．3MoO3发生晶格畸变伴随着电荷发生空间周期性调制，形成所谓的CDW。当调制波矢量q=2Kr时，布里渊区将与费米面套叠而打开一个Peierls能隙，导致体系从导体向半导体或绝     

适用于毫米波集成电路的陷波空心镜象波导

本文分析了一种新的适用于毫米波集成电路的介质波导结构陷波空心镜象波导,用等效介电常数和横向表面阻抗法从理论上分析了该结构的色散特性,并讨论了各尺寸对色散特性的影响,给出了若干数值例子。     

色散缓变光纤中五阶非线性调制不稳定性

在三五阶非线性共存时,研究了有损耗单模光纤中基于两光波交叉相位调制的不稳定条件和增益谱.在色散缓变光纤正色散区,分析了五阶非线性系数、色散纵向变化参量以及两扰动的频率大小关系对交叉相位调制不稳定增益谱的影响.结果表明,在五阶非线性下,色散的纵向渐减仍有利于展宽调制不稳定增益谱;正五阶非线性可使增益谱的谱宽和谱峰值增大,并使谱峰位置远离主波频率,负五阶非线性的作用则相反;两扰动频率大小关系不同,色散纵向参量的变化对增益谱的谱峰大小和位置的影响也不同,五阶非线性对交叉相位调制不稳定性的加强或抑制程度也不同.     

非线性双折射色散缓变光纤中极化调制不稳定性

利用光脉冲在光纤申传播时所遵守的相干非线性薛定谔耦合方程，研究了线偏振光在双折射色散缓变光纤申的传输特性．结果表明，线性双折射、非线性效应和色散的相互作用，使光的偏振状态发生变化，产生交叉相位调制(XPM)，从而导致相位匹配参量的四波混频．这一过程不仅在反常色散区产生，在正常色散区也能产生，并且当传输距离发生变化时，也随之发生变化．     

双正弦周期调制介质波导的色散特性及其应用

本文根据Fourie变换理论,推导了电磁波在双正弦周期调制介质中的传播特性,求解了上述条件下电磁场边值问题的特征值和相应的特征向量问题。通过数值计算,得到了一组描述此种介质中电磁波的色散特性。同时,找到某些不同于单正弦周期介质中传播特性的结果。最后,介绍了一种新型的双阻带介质波导滤波器作为它的应用实例。     

绝缘无辐射介质波导中耦合线分析

本文利用横向滔振法，导出了绝缘无辐射介质波导中耦合线的特征方程，并导出了弱耦合情况下的耦合系数。     

Longitudinal Wave Propagation in Dielectric Waveguide Array

Based on the established rigorous theory for two-dimensionally periodic (2DP) medium, Longitudinal propagation in Dielectric Waveguide Array (DWA) was analyzed in detail. Firstly, given longitudinal wave vector (k _z), Brillouin dispersion relations between transversal wave vectors were analyzed. Interactions between space harmonics were also studied. Secondly, on condition that transversal wave vector k _x equaled k _y, dispersion relations between longitudinal and transversal wave vectors were analyzed in detail. Because of interactions between space harmonics increasingly getting stronger with k _z or modulation coefficients increasing, stop-bands could be distinctly displayed and thus longitudinal propagation in DWA could be comprehensively analyzed. The applications about longitudinal propagation in DWA were also discussed.     

Rigorous Analysis of Electromagnetic Wave Propagation in Cylindrical Dielectric Waveguide Array

Cylindrical Dielectric Waveguide Array(CDWA) should be considered as a kind of two-dimensionally periodic(2DP) medium. Based on the established rigorous theory for 2DP medium, a great amount of numerical results for CDWA were presented. Wave propagation in CDWA was analyzed in detail in this paper. Firstly, given the longitudinal wave vector (k _z=0), Brillouin dispersion relations between transverse wave vectors were analyzed when modulation coefficients or the rate of different dielectric areas in a unit cell varied. Interactions between space harmonics were also studied. Secondly, when the area of dielectric cylinder in the unit cell varied within a given range, CDWA dispersion relations were compared with Rectangle Dielectric Waveguide Array's, some interesting conclusions were obtained.     

Wave Propagation in Sinusoidally Stratified Dielectric Media

The dispersion properties and the fields of electromagnetic waves are investigated for propagation in a stratified infinite medium. The stratification is characterized by a dielectric constant which, along one coordinate, is modulated sinusoidally about an average value. A systematic and comprehensive study is presented for the case of H modes for which the pertinent wave equation is in the form of a Mathieu differential equation. The modes and dispersion characteristics are analyzed in terms of a "stability" chart, which is customary in the study of the Mathieu equation. Results are obtained for an unbounded medium and for a waveguide filled with the modulated medium. Also, the reflection occurring at an interface between free space and a semi-infinite medium of this type is examined. In addition to these rigorous results for arbitrary values of modulation, simple analytical expressions are given for all of these cases where the modulation in the dielectric is small. It is shown that the fields are then expressible in terms of the fundamental and the two nearest space harmonics. The fields within a unit cell in the stratified medium are calculated for both small and large modulation and for frequencies up through the second pass band. It is of interest that the variation of the fields is not, in general, simply related to the variation of the dielectric constant within a cell.     

Propagation Constants for TE and TM Surface Waves on an Anisotropic Dielectric Cylinder

Maxwell's equations for wave propagation in a cylindrical anisotropic dielectric rod have been solved for various values of the longitudinal and transverse dielectric constants with the help of an IBM 7090 computer. The solutions are limited to modes having no rotational dependence about the direction of propagation. Families of curves for various ratios of longitudinal to transverse dielectric constants are given, showing the relationship between the guided wavelength and the diameter of the rod. Equations for the cutoff and asymptotic behavior are also given.     

The Amplitude of Longitudinal Characteristic Modes in Dielectric Waveguide Array

It's not adequate to just obtain eigenvalue for solving eigenvalue problem. Since the eigenvalues associated with longitudinal characteristic modes in dielectric waveguide array (DWA) has been studied, the paper concentrates on the corresponding eigenvector, namely, the amplitude of these characteristic modes. Through numerical study of the amplitude of longitudinal guided TE and TM modes in DWA, space harmonic (SH) coupling and energy conversion effect have been discovered. The paper not only contribute to deep understand the mechanism of SH interaction, but also do good to analyze the resonance, radiation problem in DWA.     

Transverse Propagation in Dielectric Waveguide Array

Transverse propagation eigen equations for dielectric waveguide array (DWA) are derived and eigen solutions can be uncoupled into TE and TM modes. Numerical results shows that much stronger space harmonic interaction exists so that a series of interesting physical effect of canonical two-dimensionally periodic (2DP) medium can obviously be observed in DWA and related devices can be predicted, designed and realized much easier.     

A 3-D space vector modulation generalized algorithm for multilevel converters

A three-dimensional (3-D) space vector algorithm of multilevel converters for compensating harmonics and zero sequence in three-phase four-wire systems with neutral is presented. The low computational cost of the proposed method is always the same and it is independent of the number of levels of the converter. The conventional two-dimensional (2-D) space vector algorithms are particular cases of the proposed generalized modulation algorithm. In general, the presented algorithm is useful in systems with or without neutral, unbalanced load, triple harmonics and for generating 3-D control vectors.     

Propagation properties of a cylindrically polarized vector beam

A general expression for the electric field of a cylindrically polarized vector beam propagating in free space is derived on the basis of the exact fully vectorial solution of Maxwell equations in transverse Fourier space,which indicates that a cylindrical polarization can be regarded as the combination of radial and azimuthal polarizations, and the electric field retains cylindrical symmetry under the propagation. The simulation results denote that the longitudinal electric field depends on the ratio of the waist width to wavelength and the angle between the electrical vector and the radial direction; in particular, when this angle is 24.5°, a flattop intensity distribution is obtained at the plane z=0.