Scattering of electromagnetic wave by perfect electromagnetic conductor (PEMC) sphere placed in chiral media

A theoretical investigation has been carried out for electromagnetic waves scattering from a perfect electromagnetic conductor (PEMC) sphere which is placed in chiral media. The formulation of the problem is realized by expanding the incident as well as the scattered electromagnetic fields in terms of left circularly polarized (LCP) and right circularly polarized (RCP) waves. By applying the boundary conditions at the chiral-PEMC interface, eight simultaneous equations are generated, which yield the scattering coefficients associated with the Left and Right electromagnetic waves. The relative contribution of Co-polarized and Cross-polarized components of fields to the calculations of scattering cross-section is presented. The effect of admittance parameter and the effect of chirality parameter in cases of lossless, lossy permittivity and lossy permeability on Co and Cross components of scattering cross sections are observed. The results are also compared with available published literatures which are in good agreement.     

Light scattering by extraordinarily polarized polaritons

The objective of this work is to investigate how the anisotropy of the interaction between dipole-active vibrations of a crystal lattice and infrared electromagnetic waves is manifested in the spontaneous parametric light scattering spectra of polaritons (Raman scattering by small angles). The case where scattering occurs by extraordinarily polarized polaritons—quasiparticles formed as a result of the coupling of the wave polarized in the symmetry plane of a biaxial crystal simultaneously with two phonons possessing orthogonal dipolar moments—is studied. A series of spectra of equilibrium fluctuations of the electromagnetic (infrared) field, each of which represents an intensity distribution in frequency-wave number coordinates for a fixed direction of the wave vector, are constructed on the basis of a scattering model that takes account of the tensor character of the permittivity and the quadratic and cubic susceptibilities of the crystal. Analysis of the computed spectra identified the basic laws and dependences which are determined by the anisotropy of the electromagnetic susceptibilities of various orders and made it possible to explain previous experimental results which cannot be interpreted on the basis of the generally accepted model of transversely polarized polaritons. A method is proposed for determining the contributions of the dipole-active vibrations of the crystal lattice to the permittivity and the quadratic and cubic susceptibilities, as well as the absorption of the material from the spectra of the extraordinarily polarized polaritons.     

The dyadic Green's function for the cylindrical chirostrip antenna

Using the eigenfunction expansion of dyadic Green's function in unbounded chiral medium, and the method of scattering superposition, the expressions of dyadic Green's function for the one and two—layer cylindrical chirostrip antennas are derived, when the field sources are placed in any layer of cylindrical chirostrip antenna. Also, using the method of saddle point integration, the asymptotic expression of dyadic Green's function for the wraparound chirostrip antenna is obtained. The results can be directly used to analyse the radiation characteristics of cylindrical chirostrip dipolc antenna, et al.     

A phase sensitive optical rotation measurement in a scattered chiral medium using a Zeeman laser

A novel circular polarized optical heterodyne interferometer using a Zeeman laser to measure optical rotation both in nonscattered and scattered chiral medium is proposed. A pair of correlated orthogonal circular polarized light waves of different temporal frequency propagating in the chiral medium at different speed is studied. This results in phase retardation between circular polarized light waves of which the phase difference is proportional to the optical rotation angle of a linear polarized light in a chiral medium. In the mean time, two orthogonal circular polarized light waves can be treated as a circular polarized photon pair that is able to reduce the scattering effect in a scattered chiral medium. Then the optical rotation angle can be measured in the scattering medium. In addition, a common-path configuration with respect to circular polarized light waves immune the background noise. This further improves the sensitivity on optical rotation measurement based on phase difference detection.     

Broken time reversal of light interaction with planar chiral nanostructures

We report unambiguous experimental evidence of broken time-reversal symmetry for the interaction of light with an artificial nonmagnetic material. Polarized color images of planar chiral gold-on-silicon nanostructures consisting of arrays of gammadions show intriguing and unusual symmetry: structures, which are geometrically mirror images, lose their mirror symmetry in polarized light. The symmetry of images can be described only in terms of antisymmetry (black-and-white symmetry) appropriate to a time-odd process. The effect results from a transverse chiral nonlocal electromagnetic response of the structure and has some striking resemblance with the expected features of light scattering on anyon matter.     

Polarization characteristics of an electromagnetic wave scattered from a slightly random surface: +45° polarized incidence

Abstract

The present paper deals with the scattering of an obliquely polarized electromagnetic (EM) wave from a slightly rough surface, which is assumed to be a two-dimensional (2D), homogeneous and isotropic Gaussian random field. In contrast to the cases of TE(s) and TM(p) polarized incidence, the scattering profile for an obliquely polarized incidence is not symmetric with respect to the incident plane, despite the fact that the random surface is statistically isotropic.     

Scattering response of featured uniaxial anisotropic chiral medium-coated twisted PEC cylinder

Scattering of electromagnetic waves from a perfectly electrical conducting (PEC) cylinder of circular cross-section, coated with uniaxial non-magnetic chiral anisotropic medium, was discussed. A conducting sheath helix structure with adjustable pitch angle exists over the outer surface of coated cylinder, which is interfaced with the free-space. Under the uniform parallel polarized plane wave with fixed oblique incidence angle, the echo widths were determined emphasizing the other relevant scattering-related parameters (e.g. scattering/extinction efficiency etc.), taking into account different pitch angle values (of the sheath helix) and the kinds of coating mediums. The results revealed that the coating of negative uniaxial chiral medium causes enhancement in scattering efficiency (of the scatterer). Also, the scattering efficiency was found to be the same as the extinction efficiency, thereby yielding vanishing absorption of the medium. The obtained results were also compared with the situation of vanishing chirality of coating medium over the PEC cylinder; the echo width and scattering efficiency both decrease in this case.     

On the Theory of Brillouin Scattering in Piezoelectric Semiconductors with Acoustic Phonon-Conduction Electron Interaction

The theory of nonresonant Brillouin scattering in anisotropic piezoelectric semiconductors with deformation potential coupling and piezoelectric coupling between excited systems of acoustic phonons and conduction electrons is reviewed. The scattering efficiency is calculated using the appropriate dyadic electromagnetic GreeN′s function. The depletion of the scattered intensity arising from a non phase-matched scattering kinematics and from a spatial exponential decay of the sound amplitude is taken into account. The contributions to the Brillouin scattering from the free-carrier-screened indirect photoelastic effect and from the free-carrier density modulation are expressed in terms of the self-consistent electric field. This field is obtained from a Boltzmann-equation calculation of the effective ac conductivity tensor. The acoustic dispersion of the Brillouin-scattering efficiency is considered, and some possibilities of determining electronic transport properties by means of Brillouin scattering are outlined.     

Scattering forces and electromagnetic momentum density in crossed circularly polarized standing waves

We analyze the forces on a small dipolar particle and the electromagnetic momentum density in a configuration consisting in two perpendicular circularly polarized stationary waves. The field distribution shows regions in which the electric and magnetic fields are parallel corresponding to a null Poynting vector. Although the average value of the momentum density, proportional to the Poynting vector, is zero in these regions, there are scattering forces acting on small particles due to light's spin force. The total scattering force suggests a new definition of the average value of the momentum density for free propagating electromagnetic fields.     

Scattering forces and electromagnetic momentum density in crossed circularly polarized standing waves

We analyze the forces on a small dipolar particle and the electromagnetic momentum density in a configuration consisting in two perpendicular circularly polarized stationary waves. The field distribution shows regions in which the electric and magnetic fields are parallel corresponding to a null Poynting vector. Although the average value of the momentum density, proportional to the Poynting vector, is zero in these regions, there are scattering forces acting on small particles due to light's spin force. The total scattering force suggests a new definition of the average value of the momentum density for free propagating electromagnetic fields.     

Peak structure of polarized bremsstrahlung upon scattering by coupled atomic electrons

Peculiarities of polarized bremsstrahlung (PB) of relativistic electrons produced upon scattering by coupled atomic electrons are discussed; in this case, PB is regarded as scattering of virtual photons of the electromagnetic field of a fast charge by atomic electrons with their coupling taken into account. In this case, the atomic electron during scattering can acquire recoil energy only through separate portions, as a result of which the spectrum of scattered photons degenerates into a series of narrow peaks.     

Single-spin asymmetry parameter from deeply virtual Compton scattering of hadrons up to twist-3 accuracy

The study of deeply virtual Compton scattering (DVCS) has shown that electromagnetic gauge invariance requires, to leading order, not only twist-two but additional twist-three contributions. We apply this analysis and, using the Ellis-Furmanski-Petronzio factorization scheme, compute the single- (electron) spin asymmetry arising in the collision of longitudinally polarized electrons with hadrons up to twist-3 accuracy. In order to simplify the kinematics we restrict the actual calculation to pions in the chiral limit. The process is described in terms of the generalized parton distribution functions which we obtain within a bag model framework. Received: 7 November 2001 / Accepted: 25 February 2002     

Scattering of electromagnetic waves by a perfectly conducting body with a chiral coating

We propose a numerical method for solving problems of electromagnetic scattering in the resonance spectrum of frequencies by a 3D ideally conducting arbitrary-shaped body covered by a homogeneous chiral coating. A program package for calculating the characteristics of the scattered field and checking the accuracy of the obtained solution based on the above method is described briefly. Some results of numerical calculations are given, which are useful for a study of the influence of “chirality” on the scattering properties of absorbing coatings. Siberian Physical-and-Technical Institute at Tomsk State University, Tomsk, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 4, pp. 495–506, April, 1998.     

Broken enantiomeric symmetry for electromagnetic waves interacting with planar chiral nanostructures

Simulations of Maxwell’s equations for electromagnetic waves interacting with planar chiral structures are shown to depend on the polarization state of the exciting light field. These results illustrate generic features of light interaction with planar chiral structures and imply broken enantiomeric symmetry for excitation with circularly polarized light. PACS 78.67.-n; 11.30.-j     

Sum-Frequency Generation from a Thin Cylindrical Layer

In the Rayleigh–Gans–Debye approximation, we have solved the problem of the sum-frequency generation by two plane elliptically polarized electromagnetic waves from the surface of a dielectric particle of a cylindrical shape that is coated by a thin layer possessing nonlinear optical properties. The formulas that describe the sum-frequency field have been presented in the tensor and vector forms for the second-order nonlinear dielectric susceptibility tensor, which was chosen in the general form, containing chiral components. Expressions describing the sum-frequency field from the cylindrical particle ends have been obtained for the case of a nonlinear layer possessing chiral properties. Three-dimensional directivity patterns of the sum-frequency radiation have been analyzed for different combinations of parameters (angles of incidence, degrees of ellipticity, orientations of polarization ellipses, cylindrical particle dimensions). The mathematical properties of the spatial distribution functions of the sum-frequency field, which characterize the symmetry of directivity patterns, have been revealed.     

亚波长间距理想导体球阵列近区时间反演电磁场的快速求解

为快速求解亚波长间距分布的理想导体球阵列近区的时间反演电磁场,提出一种基于等效偶极子模型的解析分析方法.首先,通过分析球面波照射理想导体小球的散射场解析解发现,散射场可以近似等效为电磁偶极子辐射场的叠加.等效偶极子的强度与初始激励源的幅度成正比关系.通过建立不同小球等效偶极子矢量间的耦合方程组可以直接求解得到相应矢量的大小.然后,结合时间反演腔理论得到相应的时间反演并矢格林函数,继而得到小球阵列近区的时间反演场分布.最后,通过与数值仿真软件的计算结果进行对比,验证了方法的正确性及高效性.研究表明,时间反演技术结合近场亚波长间距小散射体加载能够实现超分辨率的场聚焦.     

Resonance radiation in electromagnetic wave scattering by a fast electron in the external magnetic field

The resonance radiation in Compton scattering of an electromagnetic wave by a fast relativistic electron moving in a given magnetic field is investigated with allowance for deceleration by the radiation. A general expression for the electric field of an arbitrarily polarized scattered wave is derived within the framework of small-perturbation theory. It is shown that the resonance peak in the scattering cross-section is caused by the small radiation friction. The dependence of the resonance line width on the characteristic parameters of the problem is examined. The scattering of a given polarized wave is considered, and the degree of linear polarization of the radiated wave under resonance is determined.Institute of Radiophysics and Electronics, Armenian Academy of Sciences, Erevan. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 10, pp. 1001–1011, October, 1995.     

Baryon chiral perturbation theory A.D. 1994

In these lectures, the status of baryon chiral perturbation theory is reviewed. Particular emphasis is put on the two-flavor sector and the physics related to electromagnetic probes. I discuss in some detail the structure of the effective Lagrangian at next-to-leading order, the meaning of low-energy theorems in Compton scattering and pion photoproduction, and confront the chiral predictions with the existing data. Some remaining problems and challenges are outlined.Lectures given at the Indian-Summer School on Electron Scattering from Nucleons and Nuclei, Prague, Czech Republic, September 1994.First, I would like to thank the organizers for their kind invitation and hospitality. I am also grateful to Véronique Bernard and Norbert Kaiser for fruitful collaborations and allowing me to present some material before publication. I would like to thank Gerhard Ecker and Jürg Gasser for sharing with me their insight into the chiral dynamics.     

Electromagnetic-wave scattering from chiral spheres in chiral media

Summary The scattering of electromagnetic waves in chiral (optically active) media from chiral spheres is studied. Mie-scattering techniques are used to find the exact solution for plane-electromagnetic-wave scattering from a chiral sphere of arbitrary size in an infinitely extended chiral medium of arbitrarily different permeability, permittivity, and chirality, and the scattering and extinction efficiencies for chiral spheres in chiral media are derived. Special cases of achiral exterior medium-chiral sphere and achiral exterior medium-achiral scatterer are considered and in the latter case well-known results of Mie scattering are recovered. Simplified results for small spheres are also found for the limit of Rayleigh scattering.