Reflection and transmission of electromagnetic plane waves from an uniaxial chiro-omega slab

Chiro-omega medium is a combination of the reciprocal chiral and omega media, and can be obtained by mixing helical and Ω — shaped wire elements in the host medium. In this article the most general uniaxial chiro-omega medium is studied. The solutions for the dispersion equations and corresponding eigenwaves are derived. Transmission and reflection properties of a chiro-omega slab at a normal incidence are studied, and the polarization, direction of the polarization ellipse, and relative powers of transmitted and reflected waves are given. The results are applied to find suitable parameters for designing a polarization transformer. These results are compared with those obtained in earlier studies on wave propagation in a free uniaxial chiral space, where the effect of the boundaries of a proposed polarization transforming device have been neglected.     

Uniaxial IB-Medium Interface and Novel Boundary Conditions

The class of uniaxial electromagnetic IB media involving five medium parameters is defined as a special case of the previously defined class of general IB media (or skewon-axion media) involving 16 parameters. The problem of plane-wave reflection from and transmission through the interface of a uniaxial IB-medium half space is analyzed. It is shown that, for general values of the medium parameters, waves polarized TE and TM with respect to the normal direction are reflected as from the respective PEC and PMC boundaries. Unlike the anisotropic soft-and-hard surface which has a somewhat similar property, the uniaxial IB interface is isotropic in the plane of the interface. As a consequence, a novel class of electromagnetic boundaries can be defined for general fields requiring vanishing of the normal components of both D and B vectors at the boundary. Another realization of such a boundary in terms of an anisotropic metamaterial with zero axial permittivity and permeability is discussed.     

A Coordinate-Free Approach to Wave Reflection from a Uniaxially Anisotropic Medium

This paper presents a coordinate-free method of solving the problem of electromagnetic wave reflection from the surface of a uniaxially anisotropic medium. Based on the direct manipulation of vectors, dyadics, and their invariants, the method eliminates the use of coordinate systems. It facilitates solutions and provides results in a greater generality. The paper contains the following results in coordinate-free forms: a) the dispersion equations; b) me directions of field vectors; c) the Poynting vectors (ray vectors) and group velocities d) the' laws of reflection and refraction; and e) the transmition and reflection coefficients. The results are valid for the incident wave having any polarization, and the optic axis of the uniaxial medium being arbitrarily oriented with respect to the interface and the plane of incidence.     

Reflection and transmission of electromagnetic waves on the interface of uniaxial chiral media

The reflection and transmission properties of plane waves on the interface of uniaxial chiral media with the optical axis parallel to the interface are investigated. The formulas of the reflected and transmitted power are derived. The curves of the group refractive angles, power of the reflected and transmitted waves for TE and TM incident waves are presented for three cases of dielectric constant combinations and for non-chiral, weak chiral and strong chiral media. Some new results are obtained, which are different from those in the uniaxial chiral media with the optical axis per-pendicular to the interface.     

双面金属包覆单轴晶体波导的偏振转换研究

利用转移矩阵方法计算了双面金属包覆单轴晶体波导结构中的色散曲线、反射谱。结果表明,双面金属包覆结构使得波导可以被自由空间光场激发;单轴晶体的光轴取向能对该结构中的波导模式进行调控,使入射光波中的Ey、Ez分量发生相互转换耦合,从而在波导层中形成杂化模。通过调节耦合金属层厚度可以对出射光偏振状态的控制,实现TE线偏振入射光向TM线偏振反射光的转换以及线偏振入射光向圆偏振反射光的转换。     

Recovery of surface orientation from diffuse polarization.

When unpolarized light is reflected from a smooth dielectric surface, it becomes partially polarized. This is due to the orientation of dipoles induced in the reflecting medium and applies to both specular and diffuse reflection. This paper is concerned with exploiting polarization by surface reflection, using images of smooth dielectric objects, to recover surface normals and, hence, height. This paper presents the underlying physics of polarization by reflection, starting with the Fresnel equations. These equations are used to interpret images taken with a linear polarizer and digital camera, revealing the shape of the objects. Experimental results are presented that illustrate that the technique is accurate near object limbs, as the theory predicts, with less precise, but still useful, results elsewhere. A detailed analysis of the accuracy of the technique for a variety of materials is presented. A method for estimating refractive indices using a laser and linear polarizer is also given.     

Propagating eigenmodes for plane waves in a uniaxial bianisotropicmedium and reflection from a planar interface

A time-harmonic electromagnetic plane wave propagating in a uniaxial bianisotropic medium is considered. Forward- and backward-propagating eigenmodes are identified, together with their dispersion equations. The eigenmodes consist of two pairs with different phase velocities, and the two components of each pair correspond to the forward and backward modes. The propagating modes are used to calculate the reflection coefficient matrix at an interface between a vacuum and a uniaxial bianisotropic half-space. Numerical results for such a reflection are presented as a function of the direction of the optical axis     

平面波在双负和双正参数媒质界面的反射与折射

研究了平面波在均匀无耗的、各向同性的、介电常数和磁导率同时为正和同时为负的媒质界面的反射与折射.理论分析了反射波和透射波在两种媒质中的传播特性,从而解释了负折射发生的原理.还给出了反射系数和透射系数的表达式.讨论了发生全反射和全折射的可能条件.     

有耗表面反射波的极化特性研究

文中对有耗媒质界面反射波的极化特性进行了较详细的分析与计算，指出此时反射波的极化与入射波的极化是不同的，给出这种变极化特性随媒质参数及入射角的各种关系曲线，这些曲线对分析雷达目标的散射极化特性是很有意义的。     

Multipath interference for in-flight antenna measurements

Formulations are presented to predict the pattern of interference (multipath) between direct rays and those reflected from the surface of the earth. These formulations can be used to assess the performance of ground-to-air, air-to-ground, ground-to-ground, and air-to-air communication and antenna measuring systems. Methods are also introduced to determine accurately the point of reflection and the path phase difference between the direct and reflected waves. Various divergence factors, used to account for energy spreading from a curved surface, are presented and compared. The formulations introduced can account for any polarization state (linear, circular, elliptical), sense of rotation (right hand, left hand), and tilt angle of the transmitting and receiving elements, and for polarization changes due to reflection.     

Plane wave propagation in a uniaxial bianisotropic medium with an application to a polarization transformer

Uniaxial bianisotropic medium is a generalization of the well-studied bi-isotropic and chiral media. It is obtained, for example, when microscopic helices with parallel axes are positioned in a host dielectric in random locations. Plane wave propagation in such a medium is studied and a simple solution for the dispersion equation and for the eigenwaves are found. As a numerical example, polarization properties of a transverse wave propagating in a uniaxial bianisotropic medium is considered. The results give a simple possibility to construct a polarization transformer with a transversely uniaxial chiral medium for changing the polarization of a propagating plane wave.     

Two time-derivative Lorentz material (2TDLM) formulation of aMaxwellian absorbing layer matched to a lossy medium

A two time-derivative Lorentz material (2TDLM) is introduced to define polarization and magnetization fields that lead to an absorbing layer that can be matched to a lossy dielectric medium. The 2TDLM is a generalization of the successful uniaxial polarization and magnetization time-derivative Lorentz material (TDLM) which has been introduced as an absorbing boundary condition for simulation regions dealing with lossless materials. Expressions are derived to describe the propagation of an arbitrary plane wave in this 2TDLM Maxwellian absorbing material. They are used to study the scattering from a semi-infinite 2TDLM half-space of an arbitrary plane wave incident upon it from a lossy isotropic dielectric medium. Matching conditions are derived which produce reflectionless transmission through such an interface for any angle of incidence and frequency. Numerical tests are given which demonstrate the effectiveness of the resulting 2TDLM absorbing layer     

Impedance matching considerations for ferrite Faraday rotators

When a linearly polarized plane wave propagates from a dielectric medium into a medium with Faraday rotation, a reflected wave will always occur at the interface. This reflection is necessary because the normal-mode wave impedances in the medium with Faraday rotation are nondegenerate, while the equivalent normal-mode wave impedances for the dielectric medium are degenerate. Therefore it is not possible to match both normal modes simultaneously at the interface. This paper investigates the peculiar reflected wave associated with impedance matching of Faraday rotators, and shows that it should have minimal impact on practical devices.     

Reflection at a Curved Dielectric Lnterface--- Electromagnetic Tunneling

The reflection of a locally plane wave from a curved interface between two nonabsorbing dielectric media is investigated. Our analysis is applicable to an interface of general shape, defined at each point by the two principal radii of curvature. When the wave is incident from the denser medium at angles greater than the critical angle it is only partially reflected, due to a form of electromagnetic tunneling. Generalized Fresnel transmission coefficients and an extension of Snell's law are derived to account for this transmission into the less dense medium. Ray tracing can then be applied to determine such phenomena as the bending losses in optical slab waveguides, and the curvature loss of skew rays within straight optical waveguides of circular cross section.     

Electromagnetic reflection from a curved dielectric interface

The reflection of a high-frequency electromagnetic field from an arbitrarily curved dielectric interface is considered. The fields are expanded in asymptotic series ofk^{-1}, known as Luneburg-Kline expansions. Based on a ray method the zero- and first-order terms ofk^{-1}of the reflected and transmitted field are evaluated at the interface. Associated with the fields at the interface, effective surface current densities can be used to determine the reflected and transmitted field at points away from the interface, which is done analytically for the reflected far field in the case of plane wave incidence. The result consists of a frequency-independent term, which is related to geometrical optics solution, and a term ofk^{-1}, which is a useful extension of geometrical optics solution in some cases.     

板状非线性介质表面耦合波的反射和透射

本文详细分析了平面波激励非线性介质后介质的非线性极化、麦克斯专方程及其解、广义的反射和透射定律；导出了板状非线性介质表面任意阶耦合波的反射场和透射场；对介质满足相位匹配和泵浦波正入射下的场进行了深入的讨论；给了非线性介质表面的布儒斯特角。     

UARAC的电磁特性分析

为了解决单轴各向异性吸波涂层(UARAC)的分析和设计中所遇到的反射系数计算问题,从电磁场理论出发,导出了电磁波以任意角入射时UARAC的反射系数公式。同时,给出了计算曲线的例子,通过实例计算分析了UARAC的斜入射特性和电磁波的入射角、极化状态等对UARAC的隐身效果的影响。得到负单轴各向异性吸波涂层(MUARAC)的吸波性能优于正单轴各向异性吸波涂层(PUARAC)的吸波性能及MUARAC的吸波性能主要取决于单轴各向异性吸波材料的横向参数等结论。为UARAC的计算机辅助分析和设计提供了基础。     

在45°入射时间接测量置于空气中的介质复折射率的方法

光在45°入射时,通过置于空气中的介质表面的反射强度,可用偏振的数学描述来表达.结合光在两透明电介质分界面上的反射时的菲涅耳反射系数的复振幅rs、rp与折射介质对入射介质的介电常数ε之问有一个数学表达式:(rs-rp)/(1-rs·rp)(1-ε)/(1+ε),即可推导出介质的复数折射率表达式为:N=(rs2+1)/(rs+1)2.     

多层单轴手征类复合材料中的双重手征结构和特性

应用广义谱域指数矩阵技术，研究具有双重手征性结构的多层单轴复合手征介质层对任意极化入射平面电磁波的反射和透射特性。用数值方法分析了光轴取向、损耗、手征和非互易参数对反射和透射系数的影响。特别是交叉极化转换效应。结果表明，双各向异性单轴手征介质在新型模式极化转换器的研制等方面有重要的应用价值。     

中波红外土壤含水量的光谱偏振特性

考虑到中波红外偏振遥感受大气干扰影响较弱,将其应用于土壤含水量监测具有独特的优势和重要意义。采用中波红外光谱偏振探测手段,对不同含水量的土壤表面进行了观测,结果表明,含水土壤表面自身热辐射的偏振特性很弱,其偏振特性主要是由太阳光反射所引起,并在太阳光较强的波段上,土壤表面的偏振度与土壤含水量存在单调递增关系,为土壤含水量的航空和卫星中波红外偏振遥感技术发展提供了科学依据。