Propagation of a monochromatic electromagnetic plane wave in a medium with nonsimple motion

An exact analytical solution is obtained for the trajectory of the wave vector of a monochromatic electromagnetic plane wave in a medium with nonsimple motion. It is shown that the spatial dragging of the electromagnetic wave by the moving medium can be described correctly in the general case only if relativistic terms of order β ² are taken into account. Zh. Tekh. Fiz. 69, 97–100 (May 1999)     

Conditional and Lie Symmetry of Nonlinear Wave Equation

Abstract

Group classification of the nonlinear wave equation is carried out and the conditional invariance of the wave equation with the nonlinearity F (u) = u is found.     

2-Soliton-Solution of the Novikov-Veselov Equation

Based on a superposition method recently proposed to obtain 1-solitary wave solutions of the KdV-Burgers equation (Yuanxi and Jiashi, 2005, International Journal of Theoretical Physics 44, 293–301), we show that this method can also be used to find a 2-solitary wave solution of the Novikov-Veselov equation. Thus, it seems that the method of Yuanxi and Jiashi in general is not restricted to constructing 1-solitary wave solutions of nonlinear wave and evolution equations (NLWEEs).     

Efficient nonlinear-optical frequency conversion in periodic media in the presence of diffraction of the pump and harmonic fields

It has been predicted by Shelton and Shen [Phys. Rev. A 5, 1867 (1972)] and observed by Kajikawa et al. [Jpn. J. Appl. Phys. Lett. 31, L679 (1992)] and Yamada et al. [Appl. Phys. B 60, 485 (1995)] that the efficiency of nonlinear-optical frequency conversion increases significantly in a nonlinear periodic medium and, accordingly, the intensity of the generated harmonic increases as the fourth power of the sample thickness, as opposed to the square law observed in homogeneous media. In this paper it is shown that the same enhancement of the efficiency of nonlinear-optical frequency conversion in a nonlinear periodic medium can be achieved using an ordinary pump wave in the form of a plane wave when both the pump wave and the harmonics are diffracted by the periodic structure of the nonlinear medium. The phenomenon is analyzed quantitatively in the example of second-harmonic generation. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 12, 793–799 (25 December 1999)     

Isotope-selective femtosecond wave packet dynamics: The rare molecule

For the first time, the femtosecond real-time vibrational dynamics of the rare ^41,41K₂ isotope, excited to the electronic state, could be selectively studied by means of time-resolved three photon ionization. A vibrational period of fs is determined. Superimposed, a beat structure with a period of 20 ps is observed. A detailed Fourier analysis reveals a strong band of three lines centered around 65.5 cm^-1. A significant perturbation of the wave packet caused by spin-orbit coupling of the A and the crossing state is found. This perturbation is the reason for the fast dephasing of the initially generated wave packet within about 10 ps. The spectrogram of the real-time data shows total revivals of the wave packet at 20 ps and 40 ps. Fractional revivals are found for times around 10 ps and 30 ps. Due to high intensity effects a remarkable slightly broadened line at 90 cm^-1 appears and can be assigned to the wave packet propagation generated in the dimer's ground state by impulsive stimulated Raman scattering. Revivals of this ground state wave packet are found at 17ps and 34ps. A comparison with other isotopes of K₂ is given. Received: 9 February 1998 / Revised: 15 May 1998 / Accepted: 2 June 1998     

Effect of external electrical field on characteristics of a Lamb wave in a piezoelectric plate

The influence of a homogeneous electrical field E on the characteristics and propagation conditions of the Lamb wave in a piezoelectric crystalline plate is considered on the basis of the theory of acoustic wave propagation in piezocrystals under the effect of an external electrical field.     

Precompression of matter during radiative energy transfer in a steady-state thermonuclear burn wave

It is shown that precompression of matter ahead of the thermonuclear burn wave front can occur in the central volume of a multilayer cylindrical system under conditions of radiative energy transfer outside the region of wave propagation. The degree of compression is sufficient for the development of a self-maintained wave of fusion reactions. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 12, 783–786 (25 December 1997)     

Defect-density switching wave in crystals under pulsed laser irradiation

A model is proposed for the ignition of a defect-density switching wave in a crystal by powerful laser pulses. It is shown that the switching wave arises as a result of the nonlinear dependence of the activation energy of the defect-formation process on the strain field due to defects. The conditions under which a switching wave arises and the profile, velocity, and propagation direction of the wave are discussed. Zh. Tekh. Fiz. 68, 73–77 (August 1998)     

Giant waves in weakly crossing sea states

The formation of rogue waves in sea states with two close spectral maxima near the wave vectors k ₀ ± Δk/2 in the Fourier plane is studied through numerical simulations using a completely nonlinear model for long-crested surface waves [24]. Depending on the angle θ between the vectors k ₀ and Δk, which specifies a typical orientation of the interference stripes in the physical plane, the emerging extreme waves have a different spatial structure. If θ ≲ arctan(1/√2), then typical giant waves are relatively long fragments of essentially two-dimensional ridges separated by wide valleys and composed of alternating oblique crests and troughs. For nearly perpendicular vectors k ₀ and Δk, the interference minima develop into coherent structures similar to the dark solitons of the defocusing nonlinear Schroedinger equation and a two-dimensional killer wave looks much like a one-dimensional giant wave bounded in the transverse direction by two such dark solitons.     

Magnetostatic surface waves produced by an inhomogeneity of the anisotropy with a turning point of the spectral function on a ferromagnet surface

Magnetostatic surface waves with fixed frequency and wave vector are predicted to exist in a ferromagnet with an inhomogeneity of the magnetic anisotropy such that the spectral function has a turning point on the surface. This result is most important for the case when an external magnetic field magnetizes the ferromagnet perpendicular to its surface. The frequency of the surface wave is determined by the frequency of the magnetostatic volume wave at the surface of the ferromagnet, and the wave vector is determined by the surface values of the local magnetic anisotropy field and its derivative. Zh. Tekh. Fiz. 68, 118–123 (June 1998)     

Effect of multiple ion reflections on the structure of an ion-sound shock wave

It is shown that multiple ion reflection, arising as a result of collisional dissipation, from a shock front can produce an ion-sound shock wave with an arbitrarily large Mach number. For an exponentially small number of reflected ions, the ion-sound shock wave “degenerates” into a collisionless quasishock wave. The comparative role of viscosity and sound dispersion with different initial nonisothermality of the plasma is discussed. Zh. Tekh. Fiz. 69, 52–56 (December 1999)     

Field distribution of magnetostatic waves in a tangentially magnetized ferromagnetic slab

The field distribution of magnetostatic surface and volume waves as they propagate at an arbitrary angle to a constant field in a tangentially magnetized ferromagnetic slab (Damon-Eschbach waves) is investigated. Snapshots of the magnetic field lines of the wave are constructed. The variation of the magnetic field distribution with thickness is qualitatively identified for a volume wave as it propagates at an angle equal to the cutoff angle of the surface wave, as a result of which the sinusoidal profile of the wave over thickness almost discontinuously acquires an additional phase difference. Zh. Tekh. Fiz. 69, 82–86 (January 1999)     

Total conversion of the polarization of electromagnetic waves during excitation of cyclotron polaritons in a two-dimensional electron system

The reflection of an electromagnetic wave from a two-dimensional (2D) electron system in a magnetic field is studied. It is predicted that a p (s) polarized incident wave will be totally converted into a reflected wave with the orthogonal polarization when cyclotron polaritons are excited in the 2D system. For a high electron density in the 2D system, the effect remains very substantial in magnitude even in the presence of electron scattering. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 4, 247–252 (25 August 1999)     

Effect of pulsed excitation of a bounded medium on a plane electromagnetic wave

An analysis is made of the transformation of a plane monochromatic electromagnetic wave in response to a temporal change in the permittivity and conductivity of a semibounded medium. The change in the parameters of the medium takes the form of a rectangular pulse of arbitrary duration and amplitude. The detailed structure of the electric field and its evolutional redistribution are determined. The asymptotic formation of a backward wave is demonstrated, whose amplitude may exceed that of the primary wave for parameters typical of a semiconductor. Zh. Tekh. Fiz. 69, 84–92 (August 1999)     

A simple model of the classicalZitterbewegung: Photon wave function

We propose a simple classical model of the zitterbewegung. In this model spin is proportional to the velocity of the particle, the component parallel top is constant and the orthogonal components are oscillating with2p frequency. The quantization of the system gives wave equations for spin,0, 1/2, 1, 3/2,…, etc. respectively. These equations are convenient for massless particles. The wave equation of the spin-1, massless free particle is equivalent to the Maxwell equations and the state functions have a probability interpretation and exhibit conserved current densities. The ground state has zero energy.     

Consideration of SH-wave fundamental modes in piezoelectromagnetic plate: electrically open and magnetically open boundary conditions

This report studies the dispersive wave propagation in the transversely isotropic (6?mm) piezoelectromagnetic (PEM) plate when the mechanical, electrical, and magnetic boundary conditions for both the upper and lower free surfaces of the plate are as follows: the mechanically free, electrically open, and magnetically open surfaces. This study follows some original results obtained in book. The fundamental modes’ dispersion relations are graphically shown for the following well-known PEM composite materials: BaTiO₃–CoFe₂O₄ and PZT-5H–Terfenol-D. It is natural that for large values of the nondimensional parameter kd (k is the wave number and d is the plate half-thickness), the velocities of both the fundamental modes approach the surface shear-horizontal wave called the piezomagnetic exchange surface Melkumyan wave. It is well known that plate waves are usually utilized in the nondestructive testing and evaluation, for instance, in the airspace industry. Also, PEM materials are used as smart ones in various technical devices such as dispersive wave delay lines, (biochemi)sensors, lab-on-a-chip, etc.     

Problems of interpretation of holographic interferograms near shock wave fronts

A method of avoiding ambiguity in the interpretation of interferograms near a shock wave front is proposed. The method is based on combining the double-exposure schlieren method and holographic interferometry. Relations for calculating, on the basis of data obtained by analyzing double-exposure schlieren photographs, both the density at the shock wave front and the gradient of the density directly behind the front, which is necessary for calculating the shifts of the interference fringes near the shock wave front, are presented. Zh. Tekh. Fiz. 68, 88–91 (September 1998)     

Generation of Optical Millimeter Wave Using Two Cascaded Polarization Modulators Based on Frequency Octupling Without Filtering

Abstract

An approach to generate an optical millimeter wave is introduced with frequency octupling using two cascaded polarization modulators followed by polarizers, respectively. By adjusting the modulation indexes of polarization modulators, only the ±4th-order sidebands are generated with a pure spectrum. Since no filter is needed, the proposed technique can be used to generate a frequency-tunable millimeter wave with a large frequency-tunable range. To prove the feasibility of the proposed approach, a simulation is conducted to generate an 80-GHz millimeter wave, and then its transmission performance is checked.     

On wave solutions of a weakly nonlinear and weakly dispersive two-mode wave system

Abstract

In this paper, we introduce and study rigorously a Hamiltonian structure and soliton solutions for a weakly dissipative and weakly nonlinear medium that governs two Korteweg–de vries (KdV) wave modes. The bounded solution and traveling wave solution such as cnoidal wave and solitary wave are obtained. Subsequently, the equation is numerically solved by Fourier spectral method for its two-soliton solution. These solutions may be useful to explain the nonlinear dynamics of waves for an equation supporting multi-mode weakly dispersive and nonlinear wave medium. In addition, we give an explicit explanation of the mathematics behind the soliton phenomenon for a better understanding of the equation.     

Generalization of the Fresnel law to the case of a pressure-wave-induced displacement of the interface between acoustic media

The problem of interaction between a nonsteady-state pressure wave and a moving interface between acoustic media is analyzed and solved for the first time with allowance for a finite displacement of the interface induced by the wave. An analytic solution is obtained using a nonlinear time transformation method. Expressions are obtained for the law of motion of the interface, and for the reflected and transmitted waves as a function of the time profile of the incident wave and the acoustic characteristics of the media. Zh. Tekh. Fiz. 69, 114–115 (April 1999)