Diffraction of an electromagnetic pulse at a finite-length dielectric gradient cylinder

Effects accompanying the propagation of an electromagnetic pulse with a nanosecond edge length in a finite-length dielectric gradient circular cylinder are studied within a three-dimensional model based on Maxwell??s equations. The pulse-edge length is commensurate with the dimensions of the dielectric body being considered. The effect of the direction of electric-vector polarization on the distribution of regions of electric-field enhancement is explored. The effect of the dielectric-cylinder length on special features of the formation of electric fields both within the body and in the surrounding medium is considered.     

Arbitrary scattering of an electromagnetic zero-order Bessel beam by a dielectric sphere

Arbitrary electromagnetic (EM) scattering of a zero-order Bessel beam by a homogeneous water sphere in air is investigated. The radial components of the electric and magnetic scattering fields are expressed using a partial wave series involving the beam-shape coefficients, scattering coefficients of the sphere, and half-conical angle of the wavenumber components of the beam. The 3D scattering directivity plots in the far-field region are evaluated using a numerical integration procedure. It is shown here that shifting the sphere off the axis of wave propagation breaks the symmetry in the directivity patterns. Moreover, the scattering strongly depends on the half-cone angle of the beam. This investigation could provide a useful test of finite element codes for the evaluation of EM scattering and radiation forces, which are important in optical tweezers and related particle manipulation applications.     

Diffraction ofH-polarized electromagnetic waves by partially shielded dielectric cylinder

The potential method and Green's theorem are employed to construct various systems of hypersingular integral equations for the two-dimensional problem of diffraction of H-polarized electromagnetic waves by a dielectric cylinder of arbitrary cross-section with a longitudinally slotted metal coating. Their numerical solution is found by the method of mechanical quadratures using special interpolation formulas. The results are compared and directivity patterns are calculated for cylinders of elliptic and rectangular crosssection for various dimensions of the slots in the coating and plane-wave angles of incidence.Physics and Mechanics Institute, Academy of Sciences of Ukraine. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 36, No. 3-4, pp. 295–310, March–April, 1993.     

Plane electromagnetic wave scattering by transversely magnetized ferrite cylinder

The paper is devoted to the problem of scattering of plane electromagnetic wave by transversely magnetized ferrite cylinder. Exact analytical expressions for all partial cylindrical modes are obtained by solving Maxwell’s equations for transversely magnetized ferrite medium in cylindrical coordinate system. They are represented as the power series expansion and then are used to formulate and to solve the boundary problem. Numerical calculations of scattering patterns are also presented. Particular attention is paid to the possibility to control the scattering pattern by the external magnetic field.     

Modelling the characteristics of electromagnetic radiation scattering by an ordered assembly of dielectric cylinders

Angular dependences of electromagnetic radiation scattered by separate finite dielectric cylinders and their ordered assemblies have been numerically simulated using a volume integral equation formalism. Dependences of directional diagrams on optical-geometric parameters of both the separate finite cylinders and their spatial ordering were studied. It is shown that collective effects of a coherent nature in the assembly of spatially ordered cylinders result in a scattered radiation angular distribution that differs strongly from that obtained for a system of cylinders that are not electrodynamically coupled.     

Factors influencing electromagnetic scattering from the dielectric periodic surface

The scattering characteristics of the periodic surface of infinite and finite media are investigated in detail.The Fourier expression of the scattering field of the periodic surface is obtained in terms of Huygens' s principle and Floquet's theorem.Using the extended boundary condition method(EBCM) and T-matrix method, the scattering amplitude factor is solved,and the correctness of the algorithm is verified by use of the law of conservation of energy.The scattering cross section of the periodic surface in the infinitely long region is derived by improving the scattering cross section of the finite period surface.Furthermore, the effects of the incident wave parameters and the geometric structure parameters on the scattering of the periodic surface are analyzed and discussed.By reasonable approximation, the scattering calculation methods of infinite and finite long surfaces are unified.Besides, numerical results show that the dielectric constant of the periodic dielectric surface has a significant effect on the scattering rate and transmittance.The period and amplitude of the surface determine the number of scattering intensity peaks, and, together with the incident angle, influence the scattering intensity distribution.     

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The characteristic of electromagnetic scattering by plasma cylinder is researched in this paper. Scattered fields of the parallel-polarized wave and vertical-polarized wave by plasma cylinder are calculated and analyzed. The calculated results show that the higher the electron density, is the greater the scattering intensity in the outside of the cylinder and the higher the plasma frequency of collision, is the smaller the scattering intensity in the outside of the column. In addition, the electromagnetic wave polarization and frequency of the incident wave also have a significant impact on the scattering intensity of electromagnetic waves, the vertically polarized wave is more likely to be scattered, and the lower frequency of the incident wave is also easier to scattering. These have certain reference value for designing and studying of the plasma antenna.     

Closed solution to electromagnetic scattering of a plane wave by an eccentric cylinder coated with metamaterials

Closed series solution of electromagnetic scattering by an eccentric coated cylinder is achieved in matrix form. Diffracted field patterns are examined for an incident plane transverse magnetic (TM) wave. The solution is found by the classical separation of variables technique and the translational addition theorems. Wave transformation and orthogonality of the complex exponentials are employed to produce an infinite series. Numerical results are then shown by shortening the infinite series to a limited number of terms. Solutions are discussed for a dielectric or a metamaterial coating.     

Observation of phase-matched relativistic harmonic generation

Phase-matched relativistic harmonic generation in plasmas is observed for the first time. Third-harmonic light is detected and discriminated spectrally and angularly from the harmonics generated from competing processes. Its angular pattern is a narrow forward-directed cone, which is consistent with phase matching of a high-order transverse mode in a plasma. The signal level is found to be on the same order of magnitude for a circularly polarized pump pulse as for a linearly polarized pump pulse.     

Effects of aggregation on the electromagnetic resonance scattering of dielectric spherical objects

Summary The effects of aggregation on the electromagnetic resonance scattering by small, strongly reflecting spheres are studied. Two or more spheres are allowed to cluster together to form rather complicated anisotropic scatterers whose extinction cross-section is calculated as a function of the wave number of the incident field in the neighbourhood of the lowest resonance of the individual spheres. The macroscopic absorption coefficient of a low-density random dispersion of clusters is also calculated in the same range of wave number. The results for two-, three- and four-sphere clusters are discussed. Work supported in part by C.N.R. through the G.N.S.M. and in part by the U.S. Army European Research Office through grant DAJA45-84-C-0005 and contract DAJA37-81-C-0895.     

Observation of phase-matched optical second-harmonic generation in organic monolayers

Guided-wave second-harmonic generation using a passive planar waveguide covered with an organic nonlinear optical film as thin as a single molecular layer is demonstrated. The phase-matching condition of this process is revealed both with a high degree of waveguide-mode selectivity and a maximum in the frequency response.     

The momentum of an electromagnetic wave inside a dielectric

The problem of assigning a momentum to an electromagnetic wave packet propagating inside an insulator has become known under the name of the Abraham–Minkowski controversy. In the present paper we re-examine this issue making the hypothesis that the forces exerted on an insulator by an electromagnetic field do not distinguish between polarization and free charges. Under this assumption we show that the Abraham expression for the radiation mechanical momentum is highly favored.     

Scattering of an electromagnetic wave from a slightly random dielectric surface: Yoneda peak and Brewster angle in incoherent scattering

Abstract

The scattering of an electromagnetic wave from a two-dimensional, slightly rough dielectric surface is studied based on the stochastic functional approach. It is shown that in the case of TM(p)-polarized incidence there exists a zero in the incoherent scattering at the angle we call the ‘Brewster scattering angle’, which depends on the incident angle in contrast to the Brewster angle of coherent reflection which is independent of the incident angle, that a ‘quasi-anomalous scattering’ can generally occur in the optically denser medium at the critical angle of total reflection in both TE(s)- and TM(p)-polarized incidence, regardless of which side of the random surface is illuminated, and that the Yoneda peak in the x-ray scattering can be interpreted as a special case of the quasi-anomalous scattering which becomes sharper when the relative refractive index becomes closer to unity as in the x-ray region. Cross-polarized scattering and enhanced backscattering due to the second-order effect are also calculated.     

Theory of the scattering of an electromagnetic field in gases

It is shown that the Poynting vector in the quantum theory of radiation can always be represented in the form of the sum of coherent and incoherent parts. Equations are obtained which describe the conversion of the radiation from one part to the other.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 81–86, April, 1973.I wish to thank V. L. Bonch-Bruevich for his interest.     

Small-slope approximation for electromagnetic wave scattering at a rough interface of two dielectric half-spaces

Abstract

The small-slope approximation (SSA) for wave scattering at the rough interface of two homogeneous half-spaces is developed. This method bridges the gap between two classical approaches to the problem: the method of small perturbations and the Kirchhoff (or quasi-classical) approximation. In contrast to these theories, the SSA is applicable irrespective of the wavelength of radiation, provided that the slopes of roughness are small compared with the angles of incidence and scattering.

The resulting expressions for the SSA are given for the entries of an S-matrix that represents the scattering amplitudes of plane waves of different polarizations interacting with the rough boundary. These formulae are quite general and are valid, in fact, for waves of different origins. Apart from the shape of the boundary, some functions in these formulae are coefficients of the expansion of the S-matrix into a power series in terms of elevations. These roughness independent functions are determined by a specific scattering problem. In this paper they are calculated for the case of electromagnetic scattering at the interface of two dielectric half-spaces. In contrast to an earlier paper by the author, where only the formulae for the reflected field were presented, in this paper both reflected and transmitted fields are considered in detail.

The a priori symmetry relations that this scattering problem should obey (reciprocity and energy conservation) are formulated in terms of the S-matrix.

The statistical moments of scattering amplitudes are directly related to the mean-reflection coefficient and scattering cross sections, which are usually determined experimentally. The corresponding formulae are given here for the case of Gaussian space-homogeneous statistics of roughness.     

Quasiparticles in Raman scattering of an electromagnetic wave by an atomic condensate

Raman scattering of an intense electromagnetic wave by a free atomic Bose condensate is considered. In a system of atoms and photons, a subsystem is separated whose dynamics can be naturally described in terms of quasiparticles: quasi-atoms and quasi-photons. The dispersion laws of quasiparticles are interrupted by the instability interval. The introduction of quasiparticles within this interval is impossible, while dispersion laws that are continued formally acquire imaginary components. The dynamic scattering model is generalized by including dissipative annihilation processes of scattered photons and uncondensed atoms. A stationary solution of the corresponding quantum control equation is found, allowing the calculation of momentum distributions of real particles and quasiparticles. The outlook for the experimental detection of quasiparticles is discussed.