Dispersion Characteristics Of Electromagnetic Waves Research Articles

Double negative media based on antiferromagnetic metamaterials

The paper presents the theoretical study results of the dispersion characteristics of electromagnetic waves existing in antiferromagnetic (AFM) metamaterial. The AFM metamaterial consists of a transversely magnetized antiferromagnet, inside of which a two-dimensional periodic structure of thin conducting wires surrounded by insulators is placed. It has been established that the AFM metamaterial has two frequency ranges, in which there are backward waves, and the material pa-rameters of the medium are twice negative. The indicated areas are located in the terahertz range. Keywords: metamaterials, left-handed medium, antiferromagnetics, spin waves.

Дважды отрицательные среды на основе антиферромагнитных полупроводников для терагерцевого диапазона частот

The paper presents the results of a theoretical study of the dispersion characteristics of electromagnetic waves (EMW) existing in a transversely magnetized antiferromagnetic (AFM) semiconductor with loss. An AFM semiconductor is an infinite bi-gyrotropic medium, the effective material parameters of which are twice negative in several frequency ranges. It was found that these frequency regions are in the terahertz range and there are four backward EMEs in them, two of which are TE waves, and the other two are TM waves.

Double negative media based on antiferromagnetic semiconductors for the terahertz frequency range

The paper presents the results of a theoretical study of the dispersion characteristics of electromagnetic waves (EMW) existing in a transversely magnetized antiferromagnetic (AFM) semiconductor with loss. An AFM semiconductor is an infinite bi-gyrotropic medium, the effective material parameters of which are twice negative in several frequency ranges. It was found that these frequency bands are in the terahertz range, and there are four backward EMEs in them, two of which are TE waves, and the other two are TM waves. Keywords: left-handed media, antiferromagnets, semiconductors, spin waves.

Дважды отрицательные среды на основе антиферромагнитных метаматериалов для терагерцевого диапазона частот

The paper presents the theoretical study results of the dispersion characteristics of electromagnet-ic waves existing in antiferromagnetic (AFM) metamaterial. The AFM metamaterial consists of a transversely magnetized antiferromagnet, inside of which a two-dimensional periodic structure of thin conducting wires surrounded by insulators is placed. It has been established that the AFM metamaterial has two frequency ranges, in which there are backward waves, and the material pa-rameters of the medium are twice negative. The indicated areas are located in the terahertz range.

Strong Dispersive Propagation of Terahertz Wave: Time‐Domain Self‐Consistent Modeling of Metallic Wall Losses

AbstractThe dispersion characteristics of electromagnetic waves have led to a wide range of applications, such as pulse compression, superluminal propagation, wave tunneling effect, and electron–wave interaction. The near‐cutoff wave inside a guiding system is strong dispersive. When the wave frequency reaches the terahertz band, this strong dispersive property is extremely sensitive to the losses induced by the limited conductivity of the component. This phenomenon is traditionally investigated through perturbation of boundary conditions in the frequency domain, which does not deal well with broad‐spectrum signals. Two simple and efficient time‐domain schemes to study the strong dispersive propagation of terahertz waves are proposed. One is based on relatively concise principles, called the constant frequency method. The second is the recursive convolution method, which is suitable for dealing with a wave with wider spectrum range. The reliability of both approaches is verified by the comparison of the dispersion curves. Using the proposed methods, the pulse compression of terahertz wave inside a strong dispersive waveguide is verified in principle.

Propagation and Generation of Electromagnetic Waves at Proton Gyrofrequencies in a Relativistic Electron–Positron Plasma. I. Low-Frequency Weakly Damped Electromagnetic Waves

We consider the dispersion characteristics of electromagnetic waves in a plasma with strong magnetic field and equal content of relativistic electrons and positrons, whose synchrotron radiation can be the source of optical radiation of a pulsar. It is shown that when a small fraction of nonrelativistic protons with a nonequilibrium distribution function is present in the plasma, an effective instability can develop at frequencies below the first harmonic of the relativistic gyrofrequency of electrons, namely, at the harmonics of the proton gyrofrequency. This instability leads to the excitation of the O- and X-mode electromagnetic waves, which can, in principle, be related with the observed pulsar radiation. In part I of this paper, we study dispersion characteristics of low-frequency electromagnetic waves (with frequencies below the relativistic gyrofrequency of electrons) in an ultrarelativistic electron–positron plasma with an isotropic momentum distribution function of the particles. Instabilities of the O- and X-mode waves and the conditions of escape of the radiation from the region of strong magnetic field into a rarefied isotropic plasma will be considered in paper II. The results can be used in the interpretation of known experimental data on the dynamic pulsar radiation spectra obtained with high temporal and frequency resolution.

Influence of the Beam Self-Fields on the Dispersion Characteristics of EM Waves in a Dielectric Waveguide Filled with Plasma

Considering the self-fields of relativistic electron beam (REB), the electron beam injected in plasma will form an ion-channel, which can stably guide REB transmitted in plasma. Based on the effect of ion-channel, the EM dispersion characteristics in a dielectric waveguide filled with plasmas is studied by using linear electromagnetic (EM) hydrodynamics perturbation theory. Both the TM mode dispersion equation and the dispersion relation are derived. After that, a discussion on the conditions of Cherenkov radiation in this system is given. It was found that the betatron oscillation of the REB is one of the important factors for the slow-wave EM instability in this system. The dispersion relation is of the form of electromagnetic-electrostatic (EM-ES) hybrid mode, which is different from the case where the effect of the ion channel is neglected.

Electromagnetic waves in a relativistic plasma with a strong magnetic field

The dispersion characteristics of electromagnetic waves in a relativistic plasma having a one-dimensional distribution function established through radiation losses in a strong magnetic field are studied. It is shown that the longitudinal waves in such a plasma exist in a certain frequency interval near the plasma frequency, they propagate at small angles to the external magnetic field, and their phase velocities exceed the velocity of light, as a consequence of which the longitudinal waves do not have clear advantages over other types of waves in terms of generation (their ''Cherenkov'' generation is impossible). The dispersion properties of the electromagnetic waves in the low-frequency intervals of ..omega../sub Hi/ less than ..omega.. less than ..omega../sub He/ and ..omega.. much less than ..omega../sub Hi/ in the ''quasivacuum'' approximation (parallel bar n/sup 2/ -- 1 parallel bar much less than 1) are analogous to the properties of normal waves in a cold plasma in the corresponding frequency intervals. A distinguishing feature of a relativistic plasma is the attenuation of the waves caused by the presence in it of a continuous spectrum of gyrofrequencies and strong spatial dispersion. The instability increments of Alfven and fast magnetosonic waves, connected with the one-dimensionality of the distribution function,more » are found for quasilongitudinal propagation.« less