Cylindrical Electromagnetic Waves Research Articles

Surface plasmons of triangular cluster consisting of three 6H-SiC cylinders illuminated by H polarized cylindrical electromagnetic incident wave

The surface plasmons properties of H cylindrical wave scattered by 2D triangular cluster consisting of three silicon carbide (6H-SiC) cylinders are investigated in this paper. Rigorous numerical procedures are used to study the plasmons resonances in such structure. The behaviors of the scattering cross section, the field distribution on the cylinder’s surface, spatial structure of the near field in the cluster for its symmetrical and nonsymmetrical excitation and scattering patterns are discussed and compared for different cases in terahertz wavelength range 10.3μm - 11.0μm. It is shown that coupled plasmon resonance can be transformed into space resonance inside of the cluster. Also, it was shown the existence of two different types of the coupled plasmon resonances in terahertz wavelength range 10.3μm – 11.0μm. One of then exist for the range wavelength where relative permittivity ϵSiC of the silicon carbide 0>ϵSiC>−1 and another - where ϵSiC<−1.

Cylindrical and plane surface electromagnetic waves in laser technology of silicon surface texturing with a double femtosecond pulse

This paper presents experimental results of laser modification of the surface of monocrystalline silicon under the influence of a double femtosecond laser pulse with varying delays less than or close to the electron–phonon interaction time, as well as the results of numerical simulation of the photoexcitation of a semiconductor in the approximation of dielectric constant. It is shown that the excitation of cylindrical surface waves not only precedes the excitation of plane surface electromagnetic waves, but is also a determining factor in the cumulative change in the dielectric constant of the medium and the creation of conditions for the excitation of plane surface electromagnetic waves.

Excitation of Surface Waves during by an Inhomogeneous Electromagnetic Wave Incident on the Plasma Boundary

We have studied the excitation of surface plasma waves during the propagation of a cylindrical electromagnetic wave in a layered plasma–dielectric medium. The dielectric—vacuum—plasma and vacuum–plasma–plasma layers have been considered. It is shown that no surface waves are excited by the cylindrical electromagnetic wave at the plasma–dielectric boundary (like in the case of a plane wave). A surface wave in a layered medium is excited in a quite narrow range of frequencies and angles of propagation. We have calculated the structures of the electromagnetic field and the electromagnetic energy flux and determined the integral reflection and transmission coefficients using both numerical an analytic asymptotic methods. It is shown that the contribution of the field from the lateral wave is negligibly small in all cases.

Analytic methods for solving the cylindrical nonlinear Maxwell equations

Cylindrical electromagnetic waves propagation in inhomogeneous and nonlinear media is of great interest for theory and application, and is an extremely complicated problem which can be described by the cylindrical nonlinear Maxwell equations. In this paper, we propose a method to exactly solve the cylindrical Maxwell equations in various types of inhomogeneous nonlinear media without dispersion. The obtained solutions can be used to describe the evolution of nonlinear oscillatory system and the interaction between two radiation waves in nonlinear media. We also show some nonlinear effects, such as second harmonic generation, and sum- and difference-frequency generation, result quite naturally from the solutions.

Radio frequency heating uniformity evaluation for mid-high moisture food treated with cylindrical electromagnetic wave conductors

Abstract Non-uniform heating is an important obstacle for applying radio frequency (RF) energy in food processing, especially for the material with high moisture content. To further extend wide applications of the RF heating uniformity improvement based on our previous study with cross electromagnetic wave conductor (EWC), a novel and effective method with cylindrical electromagnetic wave conductors and cylindrical containers was introduced in this study to improve the electromagnetic energy distribution inside the sample with mid-high moisture content. The associated computer simulation model with cylindrical EWC and container was also developed and validated based on RF experimental results to evaluate the heating uniformity. The results showed that the parameters of EWC (diameter and height) had a positive effect on the RF heating uniformity index. The sample treated with cylindrical EWC had better heating uniformity but lower temperature than that treated with cross EWC based on the comparison results. The improved target uniformity index (TUI) and the decreased heating time also indicated the positive effects of cylindrical EWC. A simplified structure for cylindrical EWC was developed and evaluated by computer simulation, which may provide potential applications of the cylindrical EWC to achieve the required RF heating uniformity in mid-high moisture food.

Traveling wave solutions of the cylindrical nonlinear Maxwell's equations

Study on propagation of cylindrical electromagnetic waves in various inhomogeneous and nonlinear media is of fundamental importance, which can be described by the cylindrical nonlinear Maxwell's equations. In recent years, finding exact solutions for these equations has emerged as a popular research topic. The exact solutions play an irreplaceable role in understanding and predicting physical phenomena, and developing numerical calculation methods, and so on. However, due to the extreme complexity of nonlinear partial differential equations, exact solutions of the cylindrical Maxwell's equations were only able to be obtained in a nonlinear and nondispersive medium whose dielectric function is an exponential function in previous researches. Actually, there is no general method at present which can exactly solve arbitrary cylindrical nonlinear Maxwell's equations. Therefore, finding physically admissible solutions meeting certain particular condition for the cylindrical nonlinear Maxwell's equations might be feasible. In this paper, we discuss the traveling wave solutions which are very important in electromagnetic theory, especially in solitary wave theory. To our knowledge, research on obtaining traveling wave solutions of the cylindrical nonlinear Maxwell's equations is still lacking. The main conclusions in this paper are listed as follows. Firstly, we introduce the cylindrical nonlinear Maxwell's equations mentioned in some previous publications, which can describe cylindrical electromagnetic waves propagation in inhomogeneous nonlinear and nondispersive media. In this paper, we focus on the nondispersive media with arbitrary nonlinearity and power-law inhomogeneity. Secondly, we point out that the electric field component E of the model has no plane traveling wave solutions E=g(r-kt), after theoretical analysis and study. Then generalized traveling wave solutions in form of E=g(lnr-kt) for the electric field component are obtained by finding correct variable substitution and solving second-order nonlinear ordinary differential equation.Finally, we provide two examples to show the physical meanings of our generalized traveling wave solutions. We find that the transmitting speeds of vibrations vary with different points of the electric field. Actually, the transmitting speed of the vibration of a certain point closer to the cylinder center is lower. As a result, we observed a physical phenomenon similar to that of self-steepening. Our work can be used to analyze the electromagnetic properties of ferroelectric materials and new materials. Theoretically, it can also provide an approach to studying the cylindrical nonlinear Maxwell's equations.

Light Spins of Cylindrical Electromagnetic Waves and their Jumps across Material Interfaces in the Presence of Energy Exchange

We investigate light spins for cylindrical electromagnetic waves on resonance. To this goal, we consider both a dielectric cylinder of infinite length immersed in vacuum and a cylindrical hole punched through a dense dielectric medium. In order for waves of constant frequencies to be established through lossless media, energy absorption is allowed in the surrounding medium to compensate for radiation loss. The dispersion relation is then numerically solved for an asymmetry parameter implying a balance in energy exchange. Numerical studies are performed by varying parameters of refractive index contrast, azimuthal mode index, and size parameter of a cylindrical object. The resulting data is presented mostly in terms of a specific spin, defined as light spin per energy density. This specific spin is found to be bounded in its magnitude, with its maximum associated with either optical vortices or large rotations. Depending on parametric combinations, the specific spin could not only undergo finite jumps across the material interface but also exhibit limit behaviors.

Cylindrical electromagnetic waves with radiation and absorption of energy

Cylindrical electromagnetic waves have been examined mostly with a radiation condition applied at the radial far field. In modern optical technology, there are however growing number of applications where both radiation and absorption of energy should be taken into account. In order to illustrate the ramifications of such energy balance, we take plasmonic waves propagating around a metallic nanowire as an example. Hence, we provide both key mathematical formulas and corresponding numerical results for the collective electronic motions in resonance with electromagnetic waves. Firstly, we show theoretically why a net Poynting energy flow is directed inward to the cylindrical axis. Secondly, we invoke a Cauchy-Schwarz inequality for complex variables in deriving an upper bound on the specific transverse light spin along the axial direction. Thirdly, we could identify both first- and second-order polarizations. Overall, loss-induced and gain-compensated characteristics are illustrated for a dissipative system. In addition, the stability of neutral states are examined by relaxing the angular periodicity.

Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium.

A simple but highly efficient approach for dealing with the problem of cylindrical electromagnetic waves propagation in a nonlinear medium is proposed based on an exact solution proposed recently. We derive an analytical explicit formula, which exhibiting rich interesting nonlinear effects, to describe the propagation of any amount of cylindrical electromagnetic waves in a nonlinear medium. The results obtained by using the present method are accurately concordant with the results of using traditional coupled-wave equations. As an example of application, we discuss how a third wave affects the sum- and difference-frequency generation of two waves propagation in the nonlinear medium.

Hyperthermia applications at microwave frequencies

Short introduction to microwave hyperthermia from the point of view of biology and physics will be given firstly. The physical basis of microwave thermotherapy for cancer treatment and for other medical microwave therapeutic purposes (e.g. in cardiology, urology, surgery, physiotherapy, etc.) will be described in this talk. Different kinds of hyperthermia clinical applications will be mentioned (i.e. local, deep local, regional and intracavitary treatment). Different physical and technological approach to describe these above given different cases will be discussed. For each of these mentioned cases a different type of electromagnetic (EM) wave should be used: EM plane wave for local treatment, converging cylindrical EM wave for regional treatment and finally diverging cylindrical EM wave for intracavitary treatment. Then different types of applicators (resp. antennas) for microwave hyperthermia clinical applications will be discussed (e.g. waveguide, waveguide horn, evanescent mode, planar, array, lens, metamaterial etc. applicators). Each of these microwave technologies has its specific advantages in creation of the optimal SAR and temperature distribution in the area to be treated. It is given by its specific EM field distribution in the aperture of these applicators. And the importance of the so called treatment planning will be discussed. It is based on several different numerical methods (e.g. FDTD, FEM, MOM etc.) for calculation of the SAR in the treated area firstly and afterwards for calculation of the temperature distribution in the treated area with respect to the time, blood perfusion, etc. Last part of this presentation will be dedicated to description of clinical results of hyperthermia in cancer treatment. Importance of possibility to combine effectively hyperthermia with e.g. radiotherapy and/or chemotherapy will be underlined.

Initial value problems of cylindrical electromagnetic waves propagation in a nonlinear nondispersive medium

We introduce a simple method to estimate the accuracy of exact solutions under initial value conditions proposed by Petrov and Kudrin [Phys. Rev. Lett. 104, 190404 (2010)]. We demonstrate that even for a sufficiently weak nonlinearity, the initial value condition difference between linear and nonlinear case may be evident. Our result may be used as a criterion of employing the exact solution to deal with initial value problems of cylindrical electromagnetic wave propagation in a nonlinear nondispersive medium.

Second-harmonic generation of cylindrical electromagnetic waves propagating in an inhomogeneous and nonlinear medium

A general description of cylindrical electromagnetic waves propagating in nonlinear and inhomogeneous media is given by deducing cylindrical coupled-wave equations. Based on the cylindrical coupled-wave equations, we analyze second-harmonic generation (SHG) of some special cases of inhomogeneity, and find that the inhomogeneity of the first- and second-order polarization can influence the amplitude of the SHG. From a different point of view, exact solutions of cylindrical electromagnetic waves propagating in a nonlinear medium with a special case of inhomogeneity have been obtained previously. We show that cylindrical SHG in an inhomogeneous and nonlinear medium can also be deduced from exact solutions. As verification, we compare the results obtained from the two different methods and find that descriptions of SHG by the coupled-wave equations are in good agreement with the exact solutions.

Solutions of the cylindrical nonlinear Maxwell equations

Cylindrical nonlinear optics is a burgeoning research area which describes cylindrical electromagnetic wave propagation in nonlinear media. Finding new exact solutions for different types of nonlinearity and inhomogeneity to describe cylindrical electromagnetic wave propagation is of great interest and meaningful for theory and application. This paper gives exact solutions for the cylindrical nonlinear Maxwell equations and presents an interesting connection between the exact solutions for different cylindrical nonlinear Maxwell equations. We also provide some examples and discussion to show the application of the results we obtained. Our results provide the basis for solving complex systems of nonlinearity and inhomogeneity with simple systems.

Thickness Effects of the Metallic and the Insulating Membranes of a Cylindrical Electromagnetic Shock Wave Transducer

Thickness Effects of the Metallic and the Insulating Membranes of a Cylindrical Electromagnetic Shock Wave Transducer

Classical theory of cylindrical nonlinear optics: Sum- and difference-frequency generation

The process of two input electromagnetic waves at different frequencies overlapping in a nonlinear medium is a typical phenomenon of nonlinear optics. The traditional method of dealing with such a problem is to use the coupled-wave equations. In this paper, sum- and difference-frequency generation of cylindrical electromagnetic waves in a nonlinear medium is investigated in a different way. We use exact solutions of Maxwell's equations to describe the propagation of cylindrical electromagnetic waves in a nonlinear medium and show that sum- and difference-frequency generation comes out quite naturally from such exact solutions. For comparison, the traditional method of utilizing the coupled-wave equations is also discussed, and we find that the results obtained from the two different approaches are consistent with each other.

Classical theory of cylindrical nonlinear optics: Second-harmonic generation

The second-harmonic generation of cylindrical electromagnetic waves in a nonlinear nondispersive medium is investigated two separate ways. One method uses the exact solutions of the Maxwell equations, which describe propagation of cylindrical electromagnetic waves, and the other method uses the traditional coupled-wave equations, which are derived from the interaction between cylindrical electromagnetic waves and a nonlinear nondispersive medium. The results obtained by these two methods are concordant with each other. We also show that both methods are useful in dealing with the problem of cylindrical second-harmonic generation and each of them has particular advantages in several aspects. The method of using the exact solution can solve problems of second-harmonic generation under initial-value and boundary-value conditions and the approach of using coupled-wave equations can be directly extended to describe other nonlinear phenomena such as sum-frequency and four-wave mixing.

Exact solutions for the source-excited cylindrical electromagnetic waves in a nonlinear nondispersive medium

The behavior of electromagnetic fields in nonlinear media has been a topical problem since the discovery of materials with a nonlinearity of electromagnetic properties. The problem of finding exact solutions for the source-excited nonlinear waves in curvilinear coordinates has been regarded as unsolvable for a long time. In this work, we present the first solution of this type for a cylindrically symmetric field excited by a pulsed current filament in a nondispersive medium that is simultaneously inhomogeneous and nonlinear. Assuming that the medium has a power-law permittivity profile in the linear regime and lacks a center of inversion, we derive an exact solution for the electromagnetic field excited by a current filament in such a medium and discuss the properties of this solution.

Absorption Characteristics of Cylindrical Electromagnetic Wave Absorbers with Controlled Graded Compositions

We have been proposed functionally graded material type electromagnetic wave absorbers (FGM type EM wave Absorbers) which have an absorption layer with graded composition distribution for the improvement in absorption performance and material strength. In this paper, we investigate an electromagnetic noise problem of the FGM type EM wave absorbers for a hollow cylinder. The FGM layer which have nonhomogeneity only though the radius is considered to be multilayered absorption layers in which the material properties are homogeneous inside each layer. Incident electromagnetic wave is also assumed an electromagnetic plane wave. Therefore, the approximate analytical solutions of electromagnetic fields in the FGM layer and scatted electromagnetic fields in outer medium of the absorber are derived based on the method of separation of variables and the eigen mode expansion of cylindrical coordinate system. Numerical calculations are carried out for the FGM type EM wave absorbers composed of epoxy resin matrix and conductive titanium oxide particles. The absorption performances are quantitatively evaluated. The effects of material composition and absorption layer thickness on the absorption characteristics are then discussed. In addition, a possibility of the material design on the FGM type cylindrical absorber suitable for the absorption of EM wave and heat dissipation is suggested.

Analytic description of cylindrical electromagnetic wave propagation in an inhomogeneous nonlinear and nondispersive medium

In a recent publication [E. Y. Petrov and A. V. Kudrin, Phys. Rev. Lett. 104, 190404 (2010)], a method for constructing exact axisymmetric solutions of the Maxwell equations in a nonlinear nondispersive medium has been put forward. In this Brief Report, we will use the proposed method to deal with problems of wave propagation in an inhomogeneous nonlinear and nondispersive medium. The inhomogeneous factor is chosen in the form as r(β), where β is a certain constant. By solving the Maxwell equations an exact axisymmetric solution is obtained, starting from the corresponding solution of linear field equations, to describe the propagation of cylindrical electromagnetic waves in the medium. In the limit β→0, our solutions go into a nonlinear but homogeneous case, which is the same as prevenient results. We analyze the initial value problem and boundary value problem, to compare the differences between homogeneous and inhomogeneous conditions. It is found that the amplitude and frequency of the electromagnetic wave can be controlled with different β. Our results can be used for analysis of inhomogeneous ferroelectric resonators.

Exact Axisymmetric Solutions of the Maxwell Equations in a Nonlinear Nondispersive Medium

The features of propagation of intense waves are of great interest for theory and experiment in electrodynamics and acoustics. The behavior of nonlinear waves in a bounded volume is of special importance and, at the same time, is an extremely complicated problem. It seems almost impossible to find a rigorous solution to such a problem even for any model of nonlinearity. We obtain the first exact solution of this type. We present a new method for deriving exact solutions of the Maxwell equations in a nonlinear medium without dispersion and give examples of the obtained solutions that describe propagation of cylindrical electromagnetic waves in a nonlinear nondispersive medium and free electromagnetic oscillations in a cylindrical cavity resonator filled with such a medium.