Vol 82, No 11 (2018)

Electromagnetic waves propagating along the waveguides forming a rhombic one-dimensional lattice are considered. Two waveguides that are part of the unit cell are assumed to be made of negative-index material, while the third waveguide from the same array is composed of material with a positive refractive index and has cubic nonlinearity. The equations of tunneling-coupled solitary waves spreading in each waveguide are solved. Unlike discrete solitons, the waves are localized on the axis of waveguides, and the maximum position moves uniformly along the waveguides.

The prospects are considered for modeling processes in high-power wide-contact semiconductor lasers, allowing for limitations due to short (about 5 cm) length of coherence. The problem of determining the number of channels of generation needed to develop an adequate model of the spatial–temporal distribution of the optical field is studied as well.

Most of the effects of metamaterial physics are associated with a resonance response, particularly electric and magnetic dipole resonances. For dielectric meta atoms with high refractive indices of 3 to 10, formulas are derived that describe the positions of the first dipole resonances, the characteristic size of particles, and their refractive index. A criterion for the validity of a dipole approximation for replacing a dielectric sphere with a pair of dipoles is constructed for the first time.

The possibility is demonstrated of controlling photon spatial properties and correlations in the near field region for nonclassical squeezed light generated during parametric scattering in a nonlinear interferometer consisting of two spaced crystals. The possibilities are considered of reconstructing modes from experimentally measured covariances.

The probability of the ionization of impurities in graphene with a gap in its energy spectrum in co-directional constant and alternating electric fields is examined in the quasiclassical approximation. Analytical expressions for the probability of ionization in a constant electric field and a strong alternating electric field acting individually are obtained.

Backward collinear acousto-optic interaction (i.e., the Bragg reflection of an electromagnetic wave from an ultrasound wave in KRS-5 crystal) is considered. The main parameters of interaction are shown to depend on the wavelength of electromagnetic radiation. Particular attention is given to acoustic-optic nonreciprocal effects. The optimum spectral ranges for the application of backward collinear interaction are determined.

Ignoring relief when using means of seismic exploration based on analyzing surface wave data can result in fundamental errors. Distortions in field data caused by relief are considered. An algorithm is proposed for considering these distortions that allows the accuracy of results to be improved considerably.

Nonlinear dynamics, physical processes, and information processing in selective spiking neurons are investigated. Summation of pulse inputs are considered on the basis of the theory of quasi-periodic functions and nonlinear transformation via relaxation of the self-oscillating system of a neuron. A way of encoding input information is also considered in which the information unit is a pulse sequence, and the intensity of the input signal is encoded by a synchronous change in the frequency of the pulse sequences.

Internal waves on the Black Sea shelf are analyzed using in situ data. Inertial waves with different mechanisms of generation are identified. The phase velocity of short-period internal waves is estimated. Internal waves of the second barocline mode, whose mechanism of generation is probably determined by the decay of inertial waves, are observed. The existence of a train of second-mode internal waves is shown.

The distortion of signals propagating over satellite communication channels in the ionosphere is considered. Ways of estimating the energy losses in the correlation processing of distorted signals relative to propagation in open space are described. The energy losses for a class of signals with phase-shift keying manipulation are estimated numerically.

Features of chaotic vibrations generated in one-beam and multibeam vircators are studied. The transition to the chaotic generation is found to pass in accordance with a complex quasi-periodical dynamics, which is confirmed by the calculated Lyapunov exponents.

A database on the thermodynamic properties of materials under extreme conditions is described. The first version of the base includes tables of pressure, energy, and entropy for 103 elements of the Periodic system in wide ranges of temperature and density. The database is developed at the Keldysh Institute of Applied Matematics, Russian Academy of Sciences, and can be accessed via links http://tefis.keldysh.ru and http://tefis.ru.

An ultra high-resolution optical spectroscopy technique is proposed for measuring Zeeman and pseudo-Stark frequency splitting during optical transitions. This approach uses the change in the time shape of the echo signal upon a a weak pulse perturbation that splits the optical transition frequencies of two or more echo-active ion subgroups.

The processing of images of point-like fluorescing objects, obtained by a matrix detector in the scheme of a luminescent microscope, is considered. Analysis of model images with parameters close to experimental images of flickering single CdSe/ZnS quantum dots is presented. A scheme for obtaining information on fluctuations in fluorescence intensity is proposed.