The study treats properties of a microwave rectenna, consisting of a semiconductor diode and a spiral antenna, that has a resonant frequency of 10 GHz. The radiation pattern of the rectenna was demonstrated to be omnidirectional within a wide range of elevation angles.
Show AbstractSpecific optical eigenmodes are considered of finite clusters of metallic nanoparticles with plasmonic resonance as well as an excitation transfer along linear chain of particles between clusters. Simple analytic and physically transparent results are presented for the problem solution of collective modes exciting inside two dimensional circular clusters and the problem excitation transfer along one dimensional linear array of coupled small plasmonic spherical particles. The results are obtained with the aid of equations’ system for self-consistent currents excited inside particles by incident electromagnetic wave field. For circular cluster of particles the coupling matrix between their currents becomes under definite conditions of such favorite properties that enables one immediately to write out the Bloch–like eigenmodes with corresponding eigenfrequencies and their half widths. What is more we get also a simple analytic expressions for coupling factor between inner part of a square structure arranged in a circular shape and its bound part. Considering linear array of particles we use a closest neighbor interaction approach which makes the linear array like the electric filter. In this approximation an analytic expression are obtained for extinction rate of exciting currents’ transfer depending on array particles number and for resonance filtering frequencies.
Show AbstractMicrotubules are important cytoskeleton element of living organisms. In this research nonlinear waves in microtubules are studied, and different types of soliton solutions are derived. Soliton solutions describe propagation of polarization and deformation waves within localized structural transition in microtubule.
Show AbstractSpectral properties are investigated of one-dimensional photonic crystal with structure defect which is considered as an anisotropic nanocomposite layer embedded between two multilayer dielectric mirrors. A number of important features in the transmission spectrum of the photonic crystal are found.
Show AbstractInvestigated plasma density excitations in two-dimensional semiconductor superlattice depending on the period and the width of the potential wells, forming a superlattice. Calculations were performed on base of the quantum theory plasma oscillations in random phase approximation taking into account the umklapp processes. Estimation of parameters of superlattice was performed using the Kronig–Penney model.
Show AbstractIn present work time-frequency characteristics of sleep spindles on EEG of WAG/Rij rats were studied by means of continuous wavelet transform. General frequency structure and average length was revealed, also complex dynamics during sleep spindle was discovered and tendency to growth of frequency from beginning to end of sleep spindle was shown. Structure changes in sleep spindles caused by aging of rats and evolving of epilepsy were discovered. Dynamics of sleep spindles appearing on EEG was studied and it was shown that it could be described by means of on-off intermittency theory.
Show AbstractThe mechanism of stimulated terahertz radiation was investigated for spin–injection oscillators. The feedback performs due to semitransparent mirror arranged on the back surface of the substrate. The influence of the feedback on spectral characteristics and radiation intensities of the oscillator are discussed.
Show AbstractThe optical spectra, thermal and magnetic properties of the compound SmCr$_3$(BO$_3$)$_4$ were investigated in a wide temperature range. A series of phase transitions at temperatures of T$_1$ =8,0 ± 0,5К, T$_2$=6,7 ±0,5К and T$_3$=4,3 ± 0,2К. were found. First two transitions at the temperatures T1 and T2 are second order phase transitions and, most likely, correspond to antiferromagnetic ordering of subsystem Cr$^{3+}$ and, then, crystal transition to the ferroelectric state. First-order phase transition at a temperature of 4,2 ± 0,2K most likely corresponds to the spin-reorientation of the chromium magnetic moments.
Show AbstractThe results of numerical simulations and analysis of non-stationary dynamics of helical electron beam in the vircator with magnetron injection gun with additional braking field are presented. We have revealed the fields of the control parameters where the squeezed state is realized in such system. Peculiarities of the dynamics of the beam in squeezed state are analyzed. By means of Karhunen–Louve decomposition the processes of appearance and propagation in the beam in squeezed state of the space-charge wave are analyzed.
Show AbstractThe results of numerical simulation of self-oscillations in a two-stage ring oscillator with active cells of Van der Pol are presented. It is shown that for large excesses of generation threshold in a system with identical cells, non-uniform spatial distribution of amplitudes of self-oscillations is observed. Regular and chaotic self-oscillations in ring DT- oscillators are investigated.
Show AbstractA new criterion for estimation of the acousto–optic interaction regimes in the acoustically anisotropic medium is offered in the report. In comparison with the conventional Klein–Cook parameter depending on the light and ultrasound wavelengths and on the interaction area length, the modified parameter also takes into consideration the acoustic energy walkoff.
Show AbstractIn this work we consider the problem of the propagation and interaction of two ultra-short optical pulses in silicene. Electrons are described in the long-wave approximation of effective Hamiltonian at the low temperature. The dependence on the velocity and amplitude of pulse was obtained.
Show AbstractThe formation of a periodic sequence of pulses generated by the line of the active cyclotron oscillator when exposed to an external short electromagnetic pulse was investigated by the methods of computational experiment.
Show AbstractThe results of experiments on the use of a liquid crystal tunable focusator, for the formation and dynamic control of so-called contour optical traps, are presented. The generated traps were further used for the manipulation of various micro–objects.
Show AbstractThe results of experimental study of the behavior of the refractive indices of the cell with a ferroelectric liquid crystal with subwavelength helix pitch are presented for the case when helix axis is oriented along the substrate.
Show AbstractThe amplitudes of standing shear wave harmonics were measured in a resonator filled with inhomogeneous cubically nonlinear medium. The inhomogeneities lead to quadratic nonlinearity appearance which is absent in homogeneous medium. Quadratic nonlinearity contribution in nonlinear effects development was estimated.
Show AbstractThe quasienergy spectrum of graphene superlattice under high-frequency electromagnetic radiation was found. The d’Alembert equation was shown to take the form of double sine-Gordon equation under the certain conditions. The solutions corresponding to the solitary electromagnetic waves were derived. The shapes and areas of these waves depend on the amplitude of the high-frequency field.
Show AbstractThe paper is devoted to investigation of cadmium selenide quantum dots doped in the liquid crystalline matrix of cadmium caprylate. Fluorescence spectra were obtained using epi–luminescent luminescence microscopy technique at temperatures ranging from 77K to 300 K. We studied how fluorescence spectra depend on the temperature, on the size of the quantum dots, and the inhomogeneity of the objects of the investigation.
Show AbstractThe transition to chaos in semiconductor superlattice coupled to external resonant system had been investigated. We have shown that transition to chaos goes through type I intermittency in the system under study. This fact is approved by dependence of the mean laminar phase length versus criticality parameter, and form of Poincare mapping.
Show AbstractIn this paper we studied the collective dynamics of interacting elements of multilayer network of Kuramoto phase oscillators. As a result, the relationship between the macroscopic properties of the multilayer network (the resultant signals of the interacting oscillators) and microscopic parameters, characterizing its topology and temporal dynamics of the individual elements has been observed
Show AbstractWe proposed a mathematical model for the study of the spatio-temporal dynamics of charge on the Ohmic contacts of the semiconductor nanostructures (superlattice). Using the developed model, we study the processes, accompanying the transition of the domain of charge, formed in semiconductor structure GaAs-AlGaAs, to the collector contact. We also discussed the influence of the collector parameters on the characteristics of domain generation.
Show AbstractA new scheme of full-field optical coherent microscope with data registration in spectral domain is described. It is based on utilization of the wide-band light source and spectral tuning by the imaging acousto–optic filter installed in the registration channel of Michelson interferometer. The experimental results are presented. It is shown that this scheme is applicable for the analysis of the object properties with rather high lateral and axial resolution.
Show AbstractA brief overview is presented of studies in the field of interactions between acoustic waves in solids and micro-volumes of a liquid placed on their surface. The results obtained in the laboratory of surface acoustic waves of Acoustic Department of Physics Faculty of Moscow State University and in the foreign scientific centers are discussed
Show AbstractA model for a periodic structure in the form of two coupled magnonic crystals is derived. The resulting model is a system of four coupled nonlinear Schrцdinger equations for the amplitudes of the envelopes magnetostatic waves. Based on the model, a numerical research of reflection and transmission of such structures is conducted.
Show AbstractFor a parallel chain of inductively coupled Josephson junctions we investigated the spectral characteristics of the generation. Changes in the spectral linewidth versus the number of junctions and the coupling parameter are examined.
Show AbstractThe results of an experimental study of the optical induction of photonic diffraction structures in a photorefractive Fabry-Perot interferometer (FPI) based on lithium niobate crystal have been presented. A self-induction periodic diffraction structure in the crystal has been demonstrated experimentally. Some features of the spatial self-actions of laser beams in photorefractive Fabry-Perot interferometers based on doped with photorefractive impurities lithium niobate plates have been studied.
Show AbstractOriginal spectral methods based on unique features of acousto-optical tunable filters are described. They provide an optimization of the detection procedure, and also decrease the acquisition time and decrease the value of inaccuracy.
Show AbstractReported on a series of experimental studies of at room temperature relaxation processes in an ensemble of quantum dots in nanoscale semiconductor films using femtosecond photon echo. The results of the experimental study of the optical properties of photon echo generated in nanoscale functional films for optoelectronic element base are presented.
Show AbstractThis paper presents a brief review the modern application of wavelet transform to analyze and diagnostics various wave components in seismic survey note processing. We describe methods of analysis and research of complex noisy survey note based on various characteristics of continuous wavelet transform. In paper we show the results of discrete wavelet filtration and the benefits of using combined techniques based on discrete wavelet transform and empirical modes method. In this paper we demonstrate the results of studying and filtering actual field seismic data.
Show AbstractOn the basis of local patterns registration in fields of probing beams the possibility of identifying 1D and 2D quasicrystalline structures (including their approximants) is considered. Influence of structural defects on the shape of pattern formations is investigated.
Show AbstractThis paper presents a new approach to increase efficiency of acousto-optic interaction in far infrared at 10.6 micron wavelength due to surface plasmon resonance. Relation between optical properties of materials and efficiency of acousto–plasmon interaction was analyzed.
Show AbstractMethod for calculation of transmission and reflection coefficients of a metafilm consisting of particles with different sizes is developed. Application of the method allowed to obtain good coincidence with experimental results for metafilms consisting of spherical ferroelectric particles.
Show AbstractA new boundary conditions for decoupling of elliptically polarized eigenmodes in anisotropic optical cavity are proposed. It is shown that the optical axis twist changes the phase shift of the waves, with effective refractive indices difference greater than difference between the ordinary and the extraordinary refractive indices.
Show AbstractThe following work is devoted to the development and research of 3D model of intensive electron flow in virtual cathode generator in the framework of program CST Particle Studio. It is shown that in vircator system with additional deceleration generation appears due to the formation of two non-stationary virtual cathodes in the beam — in the drift space and in the electron gun area. The results of numerical simulation are in a good qualitative agreement with the data obtained during previous experimental research.
Show AbstractUsing the moment method the system of equations describing the dynamics of electromagnetic pulse parameters was obtained. The transversal dynamics of super-Gaussian shape pulses are considered.
Show AbstractWe study the possibility of surface plasmon polariton (SPP) pulse shape and duration manipulation on sub-picosecond timescales via a high intensity pump SPP pulse photoexciting electrons in a gold film. We present a theoretical model describing this process and show that the pump induces the phase modulation of the probe pulse leading to its compression by about 25\% and the variation of the delay between two SPP pulses up to 10 fs for the incident fluence of the pump of about 1 mJ·cm$^{−2}$.
Show AbstractThe generation of the radiation produced by the synchronously displaced electrons of a target under the influence of high-powered laser pulse and further relaxation of the system after its passage was investigated. It is shown that generation of single pulses (up to tens of periods of laser field) as well as train of oscillations is possible.
Show AbstractDesigned and manufactured liquid crystal elements with electrically controlled spatial topology of the director orientation. First implemented mode waveguide propagation of a light beam in a spatially modulated LCD cell.
Show AbstractThe results of experimental research laboratory model based on a transparent amplifier traveling-wave tube feed input for modulating the near-cathode grid and the traditional voltage supply input to the spiral delay system, shows the dependence of the gain and efficiency of the input power level for the modulation scheme with mesh obtained values of the electron efficiency 50–56% at a gain 12–13.26 dB.
Show AbstractIn our experiments, we investigate a millimeter waves absorption by wavelength 2mm in amino acids solutions by different concentration and temperature. We determine absorption coefficients in solutions of different amino acids and compare it for pure water. These results can be used for determination of liquid composition and for investigation of water molecules dynamics in solutions.
Show AbstractSemiconductor superlattices is a compound nanostructures which are possible for using for generation and control of a highfrequency oscillations. This is important problem — the effects of the interband tunneling on the complex processes in the semiconductor superlattices. It is known that applied voltage to a superlattice reduce to formation of the electronic domains moving along the structure. In this work the oscillations of the current spectrum, coupled with domains transport through a semiconductor superlattice, are studied.
Show AbstractThe interaction of short optical pulse with a moving nonlinear induced refractive index lattice was considered. The regimes of reflection, transmission and energy capture by induced structure were studied, the interacting pulses spectral characteristics were analyzed.
Show AbstractCompletely-optical self-oscillating system based on cells with thermal nonlinearity was investigated. A condition for the existence of self-oscillations of the discrete and linear version of the feedback was obtained. The theoretical calculation for the threedimensional case was undertaken.
Show AbstractIn this study a parallel chain of inductively coupled Josephson junctions described by the resistively shunted model taking into account the effect of the current fluctuations, is considered. To calculate the changes in statistical characteristics of the soliton motion time (mean and standard deviation) for the chains with various number of junctions, we develop and implement a highly parallel computational algorithm based on OpenCL software interface. A comparative analysis of the rate of computations realized by the GPU and CPU, is performed.
Show AbstractBehavior of spatially extended systems at transition from time scale synchronization regime to the asynchronous dynamics is studied. Unidirectionally coupled Pierce diodes have been chosen as a system under study. Transition from the time scale synchronization regime to the asynchronous dynamics for spatially extended systems is shown to be performed through the ring intermittency.
Show AbstractReview on low-temperature optical dephasing in impurity solid media doped with fluorescent molecules and analysis of the data obtained by different methods of selective laser spectroscopy, including the photon echo and single-molecule spectroscopy are given.
Show AbstractSoliton dymanics in Kerr medium with localized nonlinear defect was investigated. Two regimes can be observed: refraction and trapping of the soliton by the inhomogeneity as a result of their interaction. The conditions of the soliton trapping for different shapes of the defect were investigated and it was shown that the defect impact on soliton dynamics is amplified with the increase of the nonlinear coefficient gradient.
Show AbstractThis paper proposes a method of the calculation of the viscous drift on the slopes of wind waves at the initial fetch. Forming of a chain of vortices on the front slope of the waves is experimentally investigated.
Show AbstractThe problem of light propagation was considered in a two-dimensional lattice of coupled waveguides. A theory of switching and shaping of localized modes in a system of coupled waveguides was developed. Numerical simulation of light propagation in the waveguides was performed for different parameters.
Show AbstractThe results of researches and elaboration of mathematical model of the interaction of internal waves and currents are presented. It was discovered that against the background of upwelling the internal waves were developed. Under the influence of waves there were formed jets, leading to the fluctuations of the velocity of intrusion. There were proposed mechanism and mathematical model of this process.
Show AbstractIn this paper, the algorithm of error correction coding/decoding near the Shannon limit was implemented in FPGA (Fieldprogrammable gate array) for data rates up to 1 Gbit/s.
Show AbstractA review is presented of the latest theoretical and experimental results on the generation of entangled photons with tunable quantum correlations in integrated nonlinear waveguides, based on the spontaneous parametric down-conversion in the regime of quantum walks. The possibilities to map classical amplitude and phase profiles of the pump beam to the components of a biphoton wavefunction at the output, and pump filtering in waveguides with adiabatically varying parameters, are discussed.
Show AbstractRelation between a two-dimensional spectrum of an external action on a crystal surface and a three-dimensional Fourier image of an acoustical perturbation appearing in a media demonstrated. Shown that well known for isotropic optics media relations can be applied in the case of general wave process in an anisotropic media.
Show AbstractUsing methods of impedance spectroscopy study of the processes of surface segregation of cadmium atoms, running along the borders of the updated electrodes alloy Ag–Cd (Cd contents 1 at. %, is defined as the area of solid solutions of cadmium in Ag) in solutions of NaF in the range potentials ideal polarizability.
Show AbstractThe experiments on determination of the velocity of acoustic signal using optoacoustic method. The obtained results allows to offer this method to study of processes of state transition metal films chromium copper substrate. This allows you to offer this method to control the so-called «ageing» of the surface film.
Show AbstractThe paper presents the results of experimental studies of the interaction of the electron beam periodically varying diameter with an electromagnetic wave of large amplitude. Experimentally revealed the influence of various factors on the formation and size of pulsed beam current density in the bunches. Experimentally confirmed the feasibility of amplification and generation of the device with the pulsed beam. Compared with schemes with inhibition of electron beam investigated mock-up over broadband and more efficiency.
Show AbstractExperimentally studied powerful semiconductor lasers based on AlGaAs/InGaAsP/InGaAs quantum well heterostructure and asymmetric extended waveguide. The proposed physical model explaining the change of lasers radiative characteristics over time.
Show AbstractThe paper deals with a numerical method for calculating the limiting current in vacuum waveguide partially filled with dielectric.
Show AbstractThe modification of Lyapunov exponents spectrum calculation approach for coupled self-oscillating systems, simulated within the framework of PIC-method (the most efficient approach for numerical simulation of beam-plasma systems with intensive electron flows), is suggested in this work. The analysis of Lyapunov exponents spectrum allows to study the nonlinear progressing in chains and networks of coupled spatially-extended self-oscillating systems and estimate the exact bound of generalized synchronization of interacting generators appearance.
Show AbstractThe present article is concerned with mechanisms formation of Bragg band gaps in ferromagnetic periodic structures that represent two coupled one-dimensional MC, whose parameters can vary, and structure type MC-ferrite film, then magnetostatic waves excite in them.
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