Discrete diffraction in a cascade-induced anisotropic lattice

The features of anisotropic discrete diffraction in a cascade-induced lattice formed by two crossed pump waves in a quadratically nonlinear medium have been studied. The transition from the diffraction of a signal beam in free space to discrete diffraction with the further capture in a waveguide in a defocusing lattice by the increasing of the pump wave intensity has been traced.     

Evanescent wave intensification in surface spin-wave acoustics and magnetic/nonmagnetic interface electrodynamics

A relation is found between the maximum intensification of an evanescent elastic shear wave excited in a magnetic field and the enhancement of the Schoch effect. The conditions necessary for the electromagnetic analog of this relation for the Goos-Hänchen effect in the case of a TM (TE) body wave beam incident from without are determined.     

Enhancing evanescent wave intensity in a ferroelectrics plate (Kretschmann geometry)

Conditions for the fourfold amplification of evanescent wave (s- or p-type) intensity are discussed for a nonmagnetic dielectric-ferroelectric plate-vacuum structure (Kretschmann geometry).     

Two-dimensional diffraction on a cylinder induced by a laser beam in a nonlinear gradient medium

A wave theory was developed and a numerical simulation performed of the diffractive flow of a signal wave around a negative inhomogeneity induced by a cylindrical pump beam in nonlinear medium while keeping both waves in the potential well. It was shown that a broad pump beam reflects a narrow signal beam. A nonlinear waveguide (a dark soliton) is described as well. These phenomena can be observed in Bose-Einstein condensate (BEC) and in a gradient waveguide.     

Energy Interval 1S–2S in Muonic Hydrogen and Helium

Journal of Experimental and Theoretical Physics - The interval of a large structure of energy spectrum (1S–2S) in muonic helium and hydrogen is calculated using a quasi-potential method in...     

Influence of the magnetic structure parity on conditions of the electromagnetic transparency of an antiferromagnetic plate

Bulletin of the Russian Academy of Sciences: Physics - Using the example of a transparent half-wave plate of a compensated antiferromagnetic with anti-symmetric magnetoelectric interaction, the...     

Diffraction of light beams in media with longitudinal-transverse inhomogeneity

A theory has been developed to describe the propagation of planar wave beams in media with linear or nonlinear susceptibility modulated in the transverse and longitudinal directions. The diffraction in curved coupled waveguides and from wedge-shaped inhomogeneities is considered. Ray trajectories are found and the Schrödinger equation for the beam envelope is solved numerically. The spatial dynamics of energy redistribution in the beam cross section is described. Conditions for suppressing the beam spread due to the refractive index modulation are found.     

Uniform Approximation by the Highest Defect Continuous Polynomial Splines: Necessary and Sufficient Optimality Conditions and Their Generalisations

In this paper necessary and sufficient optimality conditions for uniform approximation of continuous functions by polynomial splines with fixed knots are derived. The obtained results are generalisations of the existing results obtained for polynomial approximation and polynomial spline approximation. The main result is two-fold. First, the generalisation of the existing results to the case when the degree of the polynomials, which compose polynomial splines, can vary from one subinterval to another. Second, the construction of necessary and sufficient optimality conditions for polynomial spline approximation with fixed values of the splines at one or both borders of the corresponding approximation interval.