A unitary transformation of the vacuum state of the single-mode field into a pure Fock state is found. A scheme for generating a Fock state of the single-mode field is suggested as a realization of this transformation by the method of non-linear optics.
Compression of ultrashort pulses in holographic distributed feedback dye lasers is predicted and experimentally obtained due to application of the running pump wave. Sixfold compression of the laser pulse as compared to the pump pulse and the unidirectional generation mode have been achieved. On the basis of theoretical analysis of the generation process in such a laser the optimal excitation conditions are determined. CO2-laser with frequency doubling on the exit nonlinear mirror is proposed and experimentally realized.
The hierarchy was obtained of non-linear evolution equations integrable by means of the Wadati--Vonno--Ichikawa spectral problem. The modified nonlinear Schroedinger equation with a source was shown to be a hierarchy member which describes the optical pulse propagation in fibers with resonant atom impurities. The soliton solutions were also derived.
An automatic many-channel laser analyzer of disperse media is designed and made for diagnostics of oncological diseases The diagnostics is based on measurements of the scattering indicatress of laser radiation for blood cells with the subsequent reconstruction of the cell dimensions spectrum in the solution using an original technique for solving the inverse light scattering problem.
A remote technique is developed and experimentally verified of determining the spatial temperature distribution and the concentration of radiative components in inhomogeneous axially symmetrical volumes. The technique is based on computer processing of the data of measurements of spectra of intrinsic infrared emission by devices with the middle and low resolution.
A method for solving the dispersion equations for planar waveguides of an arbitrary distribution of complex permittivity has been found. It has been shown that the number of roots of the equations at the whole complex plane is infinite when the case of arbitrary waveguiding layers of finite thickness takes place. The possibilities of mode prism excitation when the roots located at the different Riemann sheets have been established. The solution of inverse problem on determination of the film complex permittivity and thickness by the m-line angular distribution treatment has been obtained.
Zone structure of quantum size multilayered CdSe/polymer systems was studied. Main mechanisms of electric field (the quadratic Stark effect) and low-intensity laser irradiation (photo-emf generation in multilayered system) affection on their optical properties are established. The "low-speed" and "high-speed" resonant optical nonlinearities are evaluated and were 3·10-8 and 2·10-8 cm2/kW accordingly, that is much more than for CdSe-containing glasses.
The forming processes of fiber-optic waveguides from fluorine doped silicatubes prepared by sol-gel technology were investigated. The quartz-quartz grad index fiber-optic waveguide samples had been manufactured. The quartz-polymer fiber-optic waveguides with the sol-gel glass core and with losses of 18 dB/km at 0.85 µm had been manufactured too.
The conditions for existence of the soliton-like solutions and those ones for approaching to soliton-like solution for system of universal nonlinear equations of F.I.Fedorov (in nondegenerate case) are obtained.
The analytic ratio connecting the degree of polarization of radiation at exit of arbitrary non-depolarizing optical system with elements of its Mueller matrix and polarization parameters of the incident wave is received within the limits of the Mueller matrix formalism. Mechanisms of increase and decrease of the degree of polarization by optical systems are investigated and interpreted at partially polarized illumination. The results obtained are prominent not only for the theory of non-depolarizing systems but also in practical aspect as a basis for adequate interpretation of calculated and experimental data.
A technology has been created to produce the integrated optoelectronic structures of the following type: "A3B5 semiconductor radiator -- insulator -- thin-film A2B6 photoresistor with positive feedback with respect to light flux". With external illumination of the structures (about 1--300 lx), the amplification of current flowing therethrough can be as high as 104. Based on these structures prototypes have been made of optoelectronic devices with new functional capabilities (optical switching and modulation, automatic control of semiconductor LED's luminance), which are promising for use in optical information processing systems, information display systems, target indicators, lightings of scales and markers in optical devices.
The photon-electron Compton scattering has been analyzed within the framework of configuration model of one-electron transfer. It is shown that the angular and energy distributions of scattered photon and recoil electron are set by the parameters of translation symmetry of the first and higher orders for superposition of initial and final states of the scattered photon. The theoretical results can be used for developing the solid-state high-energy photon detectors for X-ray and gamma-ray ranges.
A new mechanism of noise generation in avalanche photodiodes has been revealed and investigated. It consists of reabsorption of radiation arising on p-n-junctions during avalanche breakdown of semiconductor. The radiation spectrum and its intensity changes under the influence of external effects have been determined. (In cooperation with the Scientific Research Institute for Applied Physical Problems of the Belarusian State University.)
A method of soliton propagation in fiber-optic light-guides of circulator-type optical dynamic memory has been theoretically studied. The method is based on using the spectral filter and loss compensator. Numerical modeling has demonstrated the possibility of employing this method for stable transmission of soliton pulses over distances up to 104 km at the transmission rate of 40 Gbit/s.
Peculiarities have been studied of wavefront conjugation (WFC) in free-lasing radiation (~10-3s) and monopulse radiation of ruby lasers during four-wave mixing (FWM) in liquid crystal phototropic media based on thin oriented LC films activated with bleachable dyes. In both cases, the effect of anomalous increase in the FWM wave-front conjugation efficiency (up to 100%) has been found as temperature of the phototropic liquid-crystal medium (PLCM) approached the LC isotropic transition point. It is shown that the basic contribution into the WFC efficiency of both monopulse nanosecond radiation and free-lasing radiation is made by changes in the order parameter and optical anisotropy of the PLCM layer.
Production process has been developed and properties have been investigated of membranes based on porous alumina covered with deposited thin palladium alloy layers. Owing to the use of anodic alumina with graded local surface roughness, dense helium-impermeable membranes were made with Pd alloy film thickness of 150--200 nm featuring impermeability to hydrogen of 200 mol·m-2·hour-1·atm-1 at temperatures higher than 200°C. By reducing thickness of the dense layer made of noble alloy it will be possible to decrease the cost of membranes by several orders of magnitude and to sharply reduce consumption of rare and noble metals in membrane-manufacturing industry. (In cooperation with the Institute of Physical-Organic Chemistry of ASB, the Institute of Petroleum Chemistry Synthesis of the Russian Academy of Sciences and the Glasgow University, Great Britain.)
Study has been completed of the structure of radiation forward-scattered by isolated dielectric objects of micrometer size range when they were illuminated with coherent beams. It is found that this radiation has an intricate spatial interference field structure that is described by Henkel's functions of the 2-nd kind. Calculation data obtained can be used for automatic processing of spatial distribution of interference pattern amplitudes and calculating geometric and optical parameters of isolated dielectric microobjects both in laboratory and industry conditions.
A general purpose neural network simulation system consisting of a multiprocessor NERV and a host-computer Sparc-2 station connected by SBUS-VME interface is designed. Both all processing elements and their logic interconnection network provide high speed execution of logic operation like searching, comparison and sorting that dominate in evolutionary systems. Original principles of synchronization of processing elements, identification of a duration of parallel processes and optimal data representation are implemented in the system. This allows to simulate up to 106 neurons, each having 103 synapces. The system software is developed on the basis of "client--server" technology to provide simple networking interface. The software environment includes C and C++ cross-compilers, loading and control modules for NERV-programms execution, mathematical functions library, and libraries for floating point emulation and for basic neural network paradigms.
Three-dimensional mathematical model of resilient-viscoplastic deformations and computer program for this model have been developed. The program was verified on the analytical solution of D.D.Ivlev (generalized solution of Prandtl). Stability loss for subsidence of high blanks was found on the basis of this model. New analytical solution of the problem of strain of rigid-plastic strip with corner cuts was found. The special cases of the latter solution are both the solution of R.Hill, which includes a non-unique field of speeds, and the solution which includes unique field of speeds.
The common theory of multilevel decomposition, which is based on special mixed parametrization of the initial optimization problem, is developed. The parametrization allows to decompose the initial problem on the union of subproblems immersed into hierarchical family of interconnected "extended" subproblems. The common scheme of the decomposition method is worked out, the sufficient demands to basic components of decomposition scheme, providing its applicability to obtain exact or approximate solutions of the initial problem, are discovered. The properties of stationary and local minimum domains of objective functions of obtained subproblems as well as their interconnection with corresponding domains of the initial problem are established. It is shown that the number of "significant" local domains of upper level problem is not greater than the number of local domains of the initial problem.
A new approach is proposed for finding the minimum AND/EXOR implementations of incompletely specified Boolean functions. Unlike the known methods only m n-component input combinations are taken into consideration, where a regarded function is defined, and the remaining 2n-m inputs are ignored, that essentially decreases the calculation time. In case of a single Boolean function, the problem is reduced to looking for a shortest solution of a system of m linear logical equations, and this task is solved by a modified tree searching algorithm. In case of a system of Boolean functions the theory of linear vector spaces is applied for finding a minimum polynomial representation. Practically efficient exact and approximating methods for solving the considered problems were elaborated too for both single functions and system of them.
The two-phase technology of picture description processing was proposed, appropriate for solving problems of graphical data banks forming and high-quality graphical documents (plots, maps, polygraphic print originals) production, based on fast raster-to-vector conversion method. At the first (software preprocessing) phase the output pictures are decomposed on a set of symbols and standard plane figures, setting their geometrical characteristics, and their (output pictures) descriptions, ordered in accordance with demanded order of withdrawal from computer into vector-to-raster conversion processor. At the second (picture registration) phase the raster symbols and figures descriptions are formed in registration rate with aid of special hardware generators, which along with microprocessor, memory and commutation units are forming vector-to-raster processor that realizes described treatment algorithm.
For the problem of the almost decoupling disturbance the necessary and sufficient condition of the solvability is obtained for linear lumped dynamical systems in the dynamical controlled class.
A description of the cone of convexity directions is obtained for closed sets in finite-dimensional vector spaces. This gives an approach to defining new convexity measures used for shape analysis of geometric objects and in image processing.
The methods of stabilizing linear dynamic system by using positional solutions of optimal control problems with special quality criterion -- quadratic functional, control intensity, mixed (time and intensity) quality criterion -- have been developed. The problem of constructing optimal controls of feedback type is solved for a hierarchical control problem.
Numerical methods and software for simulation of the processes of the redistribution of dopant atoms during thermal processing of two-layer semiconductor structures are proposed.
The connection is received between functional derivatives and the ordered Wick polynomials in functional integrals with respect to quasimeasure defined by characteristic functional of exponential form.
The methods for formation of semiconductor nanocrystals in thin-film matrix were elaborated and the feasibility of realization of strong and fast (about 2 ps) nonlinearity on the basis of such structures was shown. By quantum chemical calculations of the electronic structure and electron absorption spectra, the interpretation of spectroscopic and luminescence properties of MgO, ZnS and CdS clusters depending on its size was given. A numerical method for calculation of the spectral characteristics of random and particular-ordered distributions of nanometer scatters have been suggested on a basis of statistical multiple scattering theory for waves. It is found that these characteristics depend on the particle packing degree and intrinsic media structure.
On the basis of pico- and nanosecond kinetics measurements of the oxygen geminate and nongeminate recombination with the heme iron the dynamics of the molecular oxygen motion in the bulk of protein is determined. It is shown that after photodissociation the efficiency of the oxygen escape from protein to the surrounding medium is regulated by three stages of geminate recombination: (i) the ultrafast (t=2·10-10 s), which corresponds to the oxygen rebinding from the heme pocket of the protein; (ii) the fast (t=1.6·10-9 s) which is a result of the rebinding from the protein matrix, and (iii) slow (t~5·10-8 s) which possibly attributes to the rebinding from the frontier arears between the protein and the surrounding media. It is shown that the impact of the ultrafast stage increases with the increase of the pH value. The heme electronic relaxation processes complete in 1 ps and observed spectral change with the several picoseconds persistence is a manifestation of a vibrational relaxation in the ground state. The results obtained give a background for the gathering investigations of the interactions between proteins and enzymes with small ligands. These data are drawn on to develop the special medicine methods for the hemoglobin control.
A new method for determination of the short-wave plasma fluctuations spectrum using the time delay of the backscattered signal near the hybrid resonance is developed. It is shown that the method have a good spatial and spectral resolution.
The dependence of the quantum yield of the infrared (IR) and visible luminescence of rare-earth ions (erbium and holmium) on their concentration in self-doped crystalline media and on the excitation wavelength has been established. The concentration quenching of the visible luminescence and the enhancement of the IR luminescence are interpreted as a manifestation of cross-relaxation interactions between the rare-earth ions, which lead to multiplication of the IR luminescence quanta. The measured values of the luminescence quantum yield reach 3. The practical applications of rare-earth luminophors are also extended.
The physical interpretation of discovered three-staged plasma formation process during one-impulse laser action on various materials under the conditions of one-dimensional erosion plasma expansion in air at atmospheric pressure is given. This process consists in initial plasma formation due to evaporation of surface impurities and defects, subsequent plasma formation at the cost of evaporation of basic target material on the leading edge of laser pulse and then step or smooth (depending on the impulse form) transition in ambient environment with creation of radiative absorption waves.
A fundamentally new technique of diamond films synthesis based on electrochemical process was developed: the composition of electrolyte was suggested in which the carbon containing ions convert into diamond-like carbon modifications when the direct current was carried throw the electrolyte/electrode boundary.
The method of electrodeposition technique has been developed for the preparation of thin-film space-modulated by magnetic ordering nanosized structures. In such CuCo films, produced by the above mentioned method, the giant isotropic magnetoresistance has been discovered, which is due to the scattering of conduction electrons on the magnones of nanosized structure elements.
The birefringence, depolarization and dichroism effects of the polarized X-ray many-wave scattering in the Laue case for highly distorted single crystals were found. The parameters of these effects are sensitive to the changing of degree of crystal defection and the diffraction conditions.
By using the "Sephadex"-type sorbents it was worked out an effective method for extracting 60C from fullerene-containg soot and its purification. Single crystals and films of fullerenes were successfully grown from materials, which was obtained for that method.
The cluster model of magnetic ordering in the solid solution system of Mn2-XFeXSb (0<X<0.7), inferring the selective distribution of iron ions in cation sublattices, has been proposed. The model enables one to account for quantitatively the anomalous behavior of the magnetic characteristics of these materials.
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A new scheme is proposed for realization of optical interconnections in integral optics which is based on the Talbot effect. Theoretical analysis and numerical calculations are performed for the Talbot models of beam self-reproduction and matrix illuminator. Experimental results are in good agreement with the theory developed.
The optical switching waves are registered for the first time which take place during optical bistable transition in thin GaAs Fabry--Perot interferometers at conditions of spatially non-uniform input light beams. The measured propagation speed of the above waves proved to be sufficient for the whole switch-on time to fit nanosecond range. Such switching waves are very promising for transportation of information signals in planar systems for optical information processing.
The dynamics of screening the space charge region near the surface of semiconductor by photo-induced carriers is studied. The switch-on response time of optical nonlinearity due to electrooptical effect in the field of space charge is shown to be in subpicosecond (10-13 s) time range.
Source: "Main Results of Fundamental Research.1995". Eds. A.M.Goncharenko and N.N.Kostyukovich. Academy of Sciences of Belarus, Minsk, 1996
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