Specific features of propagation of electromagnetic waves in layered magnetic photonic crystals

The general regularities of the evolution of the spectrum of magnetostatic waves in a periodic system composed of alternating ferromagnetic and nonmagnetic layers are analyzed. The spectrum of electromagnetic waves in an infinite periodic system and the coefficient of reflection of a plane electromagnetic wave from a half-space periodically filled with ferromagnetic and nonmagnetic layers are calculated. The dispersion relation is derived and analyzed for surface magnetostatic waves at the interface between the periodic system of layers and vacuum.     

Effect of backward radiation of electromagnetic waves by a metamaterial waveguide structure

The anomalous properties of electromagnetic radiation from an antenna in the form of a rectangular section waveguide tube made of a metamaterial with the negative real parts of permittivity and permeability have been demonstrated. The metamaterial is an isotropic two-dimensional array of left and right-twisted coils placed on a thin polyurethane substrate. The coils of the sample are directed in equal numbers along the x, y, and z axes. The possibility of the preferential backward radiation of the structure has been shown on the basis of numerical calculations with the use of the method of moments and the measurements of the radiation pattern of the antenna in an anechoic chamber at frequencies close to the 3-GHz resonance frequency of the metamaterial. The causes and existence conditions of the effect have been revealed.     

Asymmetric propagation of electromagnetic waves through a planar chiral structure

We report that normal incidence transmission of circularly polarized waves through the lossy anisotropic planar chiral structure is asymmetric in the opposite direction. The new effect is fundamentally distinct from conventional gyrotropy of bulk chiral media and the Faraday effect, where the eigenstates are a pair of counterrotating elliptical states, while the eigenstates of the lossy anisotropic planar chiral structure are two corotating elliptical polarizations.     

Specific features of neutron propagation in a medium with a helical magnetic structure

The features of neutron motion in a noncoplanar magnetic field have been considered in the example of a specific magnetization distribution in the form of a conical helix. The neutron reflectances for holmium crystals have been calculated. It is shown that, in the case of noncoplanar distribution of magnetic field in a crystal, the spin-flip neutron reflectance has an additional singularity.     

Eigen electromagnetic waves of a coaxial waveguiding structure filled by a non‐uniform dissipative plasma with azimuthal magnetic field

This paper studies the propagation and spatial attenuation of high‐frequency eigen‐symmetric and dipolar electromagnetic waves along a coaxial plasma–metal waveguiding structure that contains a slightly axial and strong radial non‐uniform cylindrical plasma slab in an external azimuthal non‐uniform magnetic field. The influence of such parameters as the effective electron collision frequency, the direct current value producing the external azimuthal magnetic field, parameters that characterize plasma density radial profile, and waveguide geometric parameters on the dispersion, spatial attenuation, and radial field structure of the waves is considered. The regions of waveguiding structure parameters where the electromagnetic wave properties can be effectively controlled are studied and analyzed.     

Specific features of light propagation in a periodic structure with regular arrangement of defect layers

Specific features of light propagation in a periodic structure with a large number of identical regularly arranged defect layers are considered. Rigorous analytical formulas for the transmittance and reflectance of the structures are derived. It is shown that the presence of periodically arranged inclusions may give rise to new photonic band gaps, with their positions controlled by the dielectric properties and thickness of the defect layers.     

Left-handed metamaterial based superlens for subwavelength imaging of electromagnetic waves

Lenses made of negative index materials have the ability to focus the propagating and evanescent components of electromagnetic waves. Such a possibility enables super resolution, in turn resulting in sharper, subwavelength size images. In this present work, we present subwavelength imaging that was obtained from a one-dimensional left-handed metamaterial (LHM) composed of alternating layers of split-ring resonators and thin wires. We investigated the effect of the thickness of LHM lenses on image size. The left-handed pass band within the negative permittivity and permeability region is shown experimentally and theoretically for different thicknesses of LHM slabs. We also studied the transmission-phase of LHMs with a different number of unit cells along the propagation direction. The phase decreases with the increasing thicknesses of LHM slabs, proving that the phase velocity is negative in the left-handed transmission band. PACS 42.25.-p; 41.20.Jb; 81.05.-t     

Control of the perturbation-wave-vector range of modulation instability of dispersive electromagnetic waves in the nonlocal Josephson electrodynamics of a thin superconducting film

Modulation instability of dispersive electromagnetic waves propagating through a Josephson junction in a thin superconducting film is investigated in the framework of the nonlocal Josephson electrodynamics. A dispersion relation is found for the time increment of small perturbations of the amplitude. For dispersive waves, it is first established that spatial nonlocality suppresses the modulation instability in the range of perturbation wave vectors 0≤Q≤Q_B1(k), i.e., in the long-wavelength range of experimental interest. The modulation instability range Q_B1(k)<Q<Q_B2(k, A, L) can be controlled (which is a unique possibility) by varying a dispersion parameter, namely, the wave vector k [or the frequency ω(k)] of linear-approximation waves. In the wave-vector ranges 0≤Q≤Q_B1(k) and Q≤Q_B2(k, A, L), waves are shown to be stable.     

Coherent phenomena in a layered superconducting metamaterial

The model of a superconducting metamaterial, which is a disordered lattice of Josephson junctions, has been studied theoretically and by computer simulation. The aim of this work is to reveal and analyze the conditions under which the generation frequencies of constituting junctions are locked in the system under study placed in a spatially nonuniform magnetic field. The main result is the demonstration of the possibility of locking of the generation frequencies of junctions in individual layers of the system under study. This result is particularly important in view of the possibility of the use of superconducting metamaterials for the creation of devices, in particular, generators capable of working in the terahertz frequency range.     

Analysis of electromagnetic propagation in birefringent thin film

Recently, a series of thin films with particular microstructure have been deposited successfully[1,2]. The thin films with regular microstructure give optical anisotropy in macroscopic view, i.e. birefringent feature. The theoretical analysis and deposition of birefringent thin film inject activity into traditional optical thin film[3―6]. Basing on the birefringent thin film, the researchers have successfully prepared electro-optic tunable filters[7], antireflection coatings[8], phase compens…     

Nonlinear propagation of relativistically intense electromagnetic waves in a collisionless plasma

We discuss the nonlinear propagation of relativistically intense electromagnetic waves into collisionless plasmas with special emphasis on one dimensional plane wave solutions of the propagating, standing and modulated types. These solutions exhibit a rich variety of phenomena associated with relativistic electron mass variation and coupling between transverse electromagnetic and longitudinal fields. They have important applications to problems of laser propagation, self-focusing in overdense plasmas, particle and photon acceleration and to electromagnetic radiation around pulsars.     

Tunneling of electromagnetic waves through a barrier with a periodic structure

The propagation of an electromagnetic wave through a barrier with a periodic structure is considered. An interesting manifestation of electromagnetic wave tunneling through a barrier with a periodic structure is revealed. Specifically, it is theoretically and experimentally shown that, when an electromagnetic wave passes through a medium with a periodic structure in the diffraction mode within a photonic band gap, the field in the medium is localized near its boundaries. Theoretical calculations have been performed for a cholesteric liquid crystal layer of finite thickness and for a 1D photonic crystal. The experiment was carried out with perfect Si single crystals in reflection from the $ (2\bar 20)$ (2\bar 20) and $ (4\bar 40)$ (4\bar 40) planes using MoK _α X rays.     

Stimulated emission of the coherent electromagnetic radiation by superconducting film

Coherent microwave radiation has been directly detected in the frequency range of 0.15–200 MHz from superconducting thin films excited by an oscillating magnetic field directed perpendicular to the film plane. Due to pinning, a metastable state of the vortex system can be set up in the superconducting films. Vortex-jump synchronization reached via their electromagnetic interaction with external resonant circuit causes the generation of the electromagnetic radiation.     

Specific features of waves in magnetic crystals

On the basis of the asymmetric velocity tensor introduced we develop an orthogonal representation of wave propagation in anisotropic magnetic dielectrics. Simple expressions are obtained for the direct dependence of polarization vectors, refractive indices, and phase and group velocities of isonormal waves in a magnetic dielectric on the vectors of principal velocities. We show that the presence of magnetic properties is manifested in the optical range in the fact that the velocities of wave propagation in uniaxial crystals are determined by three main refractive indices, and therefore, both waves except for specific directions become extraordinary, whereas in biaxial crystals (also because of a large number of parameters) the cones of internal and external refraction become elliptic. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 597–600, September–October, 1999     

Kinetic approach to the propagation of electromagnetic waves in a weakly ionized plasma

Summary High-frequency wave phenomena in a partially ionized plasma are analysed in the frame of the kinetic theory without resorting to perturbation techniques. In particular, we obtain the electron distribution function in an external electric field alternating in both time and position, and then the electrical conductivity and the dispersion relation. Corrections to the results of the macroscopic theory are evaluated up to any desired order.

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Riassunto Il fenomeno della propagazione di un'onda elettromagnetica in un plasma parzialmente ionizzato è analizzato nell'ambito della teoria cinetica. Il metodo proposto consente di ricavare la funzione di distribuzione degli elettroni senza dover ricorrere a tecniche perturbative. Si riportano le espressioni esatte della conducibilità elettrica e della legge di dispersione e, quindi, le correzioni da apportare ai risultati ottenuti con la teoria macroscopica.

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Резюме В рамках кинетической теории анализизируется явление распространения электромагнитных волн в частично ионизованной плазме. Предложенный метод позволяет получить электронную функцию распределения во внешнем электрическом поле без использования теории возмущений. Затем определяются электрическая проводимость и дисперсионное соотношение. Поправки к резулятатам макроскопической теории оцениваются в любом желаемом порядке.

     

Wave propagation in a one-dimensional photonic crystal with metamaterial

This paper deals with the study of the transmission of electromagnetic waves through a one-dimensional multilayer periodic structure consisting of alternating slabs of negative- and positive-index media. It also focuses on the behavior of the transmission with the angle of incidence for both polarizations. The proposed structure works as a tunable p-polarization filter i.e. a filter which completely blocks the s-polarized wave but partially allows the p-polarized wave to pass through it for an angle of incidence greater than 20 ^°. For angles of incidence less than 50 ^° the structure works as a tunable edge filter.