| Growth of Acousto-Optic Crystals for Applications in Infrared Region of Spectrum |
30 Apr 2005 |
15 pages |
| Authors:
Vitaly B Voloshinov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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 | Acousto-optic (AO) modulators, deflectors, filters offer convenience, reliability, compact size and fast speed in regulation of optical beams. So far there are only a few AO materials available for use in the long infrared region of spectrum. The major disadvantage of such AO materials is the extremely low acousto-optic figure of merit, which automatically results in high requirements on driving electric power and poor diffraction efficiency. It is expected that ... |
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| Plasma-Jet Studies for Plasma Chemical Fuel Activation |
Jan 2005 |
109 pages |
| Authors:
Vladimir L Bytchkov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| This report results from a contract tasking M.V. Lomonosov Moscow State University, as follows: Plasma chemistry mechanisms for accelerating activation of fuels by projected plasma jets will be investigated by the team of Moscow State University (MSU). The approach will exploit excited state transitions and related dissociation processes, instead of the conventional paradigm that uses plasma-dynamic discharge, stimulating fuel ignition with short powerful ultra-violet radiation pulses that creates plasma electrons ... |
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| Optical Limiting in Photonic Crystal Fibers |
DEC 2004 |
8 pages |
| Authors:
Mark Bloemer; Michael Scalora; Wayne Davenport; Evgeni Poliakov; S. O. Konorov; D. A. Sidorov-Biryukov; E. E. Serebryannikov; A. M. Zheltikov; R. B. Miles; I. Bugar; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| Optical limiters provide sensor protection from laser energy by clamping the energy at a safe level. We present theoretical and experimental results on a new type of optical limiter based on self phase modulation and photonic crystal fibers. This unique combination allows one to engineer the limiting energy level by designing the fiber parameters to suit the particular application. We have shown that the limiting energy depends on the effective ... |
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| Surface Microwave and Surface Transversal Pulsed-Periodic Discharges in Supersonic Flow |
MAR 2004 |
267 pages |
| Authors:
Valery Shibkov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| This report results from a contract tasking Moscow State University (MSU) as follows: The contractor will develop methods of creation of plasmas of different types of gas discharges near the surface of Aerodynamic models and in the boundary layers. Also, the contractor will develop modes of internal and external fuel ignition of propane-air and hydrogen-air mixtures. He will develop methods of analysis of plasma properties in plasma regions near the ... |
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| Development of Methods for Diagnostics of Discharges in Supersonic Flows |
MAR 2004 |
149 pages |
| Authors:
Alexei Ershov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| This report results from a contract tasking M.V. Lomonosov Moscow State University (MSU) as follows: The contractor will develop methods of measurements of plasma parameters of the electric discharges in supersonic air flows of propane-air mixtures. The experimental investigation of spatial and temporary evolution of parameters of plasma discharges of various types of the discharges (longitudinal direct current, transversal pulsed-periodic, plasma dynamic discharges) and combustion plasma in supersonic flows will ... |
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| Hollow-Core Photonic-Crystal Fibres for Laser Dentistry |
Jan 2004 |
11 pages |
| Authors:
Stanislav O Konorov; Vladimir P Mitrokhin; Andrei B Fedotov; Dmitrii A Sidorov-Biryukov; Valentin I Beloglazov; Nina B Skibina; Ernst Wintner; Michael Scalora; Aleksei M Zheltikov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| Hollow-core photonic-crystal fibres (PCFs) for the delivery of high-fluence laser radiation capable of ablating tooth enamel are developed. Sequences of picosecond pulses of 1.06 m Nd:YAG-laser radiation with a total energy of about 2 mJ are transmitted through a hollow-core photonic-crystal fibre with a core diameter of approximately 14 m and are focused on a tooth surface in vitro to ablate dental tissue. The hollow-core PCF is shown to support ... |
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| Burning of the Supersonic Propane-Air Mixture in the Aerodynamic Channel With the Stagnant Zone |
20 OCT 2003 |
11 pages |
| Authors:
V. M. Shibkov; V. A. Chernikov; A. P. Ershov; A. A. Karachev; R. S. Konstantinovskij; A. V. Voskanyan; V. V. Zlobin; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| In the report the pulsed-periodical discharges created on an external surface of a flat plate being flown around of supersonic airflow and under condition of a stagnant zone located on a wide wall of the aerodynamic channel of rectangular section were investigated. It was show that the surface pulsed- periodical discharge results to ignition beforehand mixed supersonic propane-air fuel in the aerodynamic channel. In experimental conditions the combustion front speed ... |
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| Parameters of Electrode Ignition Discharges in Supersonic Propane-Air Flows |
20 OCT 2003 |
11 pages |
| Authors:
A . P. Ershov; O. S. Surkont; I. B. Timofeev; V. A. Chernikov; V. M. Shibkov; N. V. Ardelyan; S. N. Chuvashev; V. L. Bychkov; V. G. Gromov; V. A. Levin; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| Effective solution of such aerodynamic problem as fuel ignition in ramjets at supersonic velocities is evidently impossible without an application of plasma technologies. In presented work we expose results of experimental and theoretical investigations of ignition process of supersonic propane-air flows with a help of transversal and longitudinal discharges. |
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| RF Discharge at Medium and High Pressure and Its Possibilities for Material Surface Modification |
OCT 2003 |
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| Authors:
A. F. Alexandrov; G. E. Bugrov; E. A. Kralkina; V. B. Pavlov; V. Plaksin; V. P. Savinov; V. Yu. Sergeenko; I. B. Timofeev; K. V. Vavilin; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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 | During last years the tendency became evident to develop and utilize discharge at medium and high pressure in industry especially for plasma chemical applications and surface modification of materials. The review of the literature 1 devoted to this subjects, on the one hand specifies wide opportunities of such discharges and on the other hand demonstrates absence of detailed understanding of physical processes mechanisms in medium and high pressure discharges as ... |
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| Lead Telluride-based Far-infrared Photodetectors. A Promising Alternative to Doped Si and Ge |
JAN 2002 |
6 pages |
| Authors:
Dmitriy Dolzhenko; Ivan Ivanchik; Dmitriy Khokhlov; Konstantin Kristovskiy; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| Doping of the lead telluride and related alloys with the group III impurities results in appearance of unique physical features of the material, such as persistent photoresponse, enhanced responsive quantum efficiency (up to 100 photoelectrons/incident photon), radiation hardness and many others. We review physical principles of operation of the photodetecting devices based on the group III-doped IV-VI including possibilities of fast quenching of the persistent photoresponse, construction of a focal-plane ... |
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| Investigation of Discharges Influence on Boundary Layer in Supersonic Airflow |
OCT 2001 |
116 pages |
| Authors:
Valery Shibkov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| This report results from a contract tasking Moscow State University (MSU) as follows: The contractor will develop methods of creation of plasmas of different types of gas discharges near the surface of airplanes and in the boundary layers. He will also develop methods of analysis of plasma properties in plasma regions near the surface. The following experimental work will be done in supersonic air flow (M<2) at pressures between 1 ... |
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| Development of Methods for Diagnostics of Discharges in Supersonic Flows |
SEP 2001 |
224 pages |
| Authors:
Alexey P. Ershov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| The application of three independent methods of plasma diagnostics probe, spectroscopic and microwave - for diagnostics of discharges in supersonic gas flows has been investigated. |
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| On the Conduction Mechanism in Granular Materials |
JUN 2001 |
4 pages |
| Authors:
I. P. Zvyagin; R. Keiper; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| We discuss the effect of virtual intermediate localized states on inter-grain tunneling that controls conduction in granular conductors on the insulating side of the metal-insulator transition. It is shown that intermediate states can substantially increase inter-grain tunneling transition probabilities and give rise to the conductivity temperature dependence of the form ln(sigma) ^ -(T(0)/T), where x approximately equal 0.4, and to a large enhancement of the conductivity. |
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| Optical Properties of CdS Nanostructures Crystallized in the Pores of Insulating Template |
JUN 2001 |
4 pages |
| Authors:
V. Dneprovskii; S. Gavrilov; E. Muljarov; A. Syrnicov; E. Zhukov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| The characteristic features of the luminescence spectra obtained at different polarization of the exciting light beam and time resolved luminescence spectra of CdS nanocrystals crystallized in 8-10 nm diameter hollow channels of a dielectric Al2O3 template have been explained in terms of exciton transitions in semiconductor dielectric quantum wires. In these structures the dielectric confinement effect leads to a considerable increase of the exciton binding energy - the Coulomb attraction ... |
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| Optical Dichroism of Homeotropically Oriented Films of Comb-Shaped Liquid Crystal Polymer |
29 SEP 2000 |
4 pages |
| Authors:
D. F. Kiselev; T. M. Glushkova; S. A. Ivanov; M. M. Firsova; A. P. Shtyrkova; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| In this work the polarization absorption spectrum of homeotropically oriented comb-shaped liquid crystal polymer (LCP) film interposed in the electrooptical cell was investigated. The optical parameters of electrodes and polymer were estimated from the observed absorption spectra of the cell with and without polymer film using the method of interferometric extrema envelopes. This method enabled us to re-establish the true polarization absorption spectrum of the polymer. For this purpose the ... |
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| Ferroelectric-Paraelectric Phase Transitions in P(VDF-TrFE) Langmuir-Blodgett Films Studies by Optical Second Harmonic Generation |
23 JUN 2000 |
3 pages |
| Authors:
Yu. G. Fokin; T. V. Misuryaev; T. V. Murzina; V. M. Fridkin; S. P. Palto; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| Ferroelectric-paraelectric phase transitions are studied in Langmuir-Blodgett (LB) films of vinylidene fluoride with trifluoroethylene (P(VDF-TrFE)) by an electrpde-free method of optical second harmonic generation (SHG). The temperature dependences of the SHG intensity are studied for the LB films of the thickness down to a monolayer and two peculiarities attributed to two different ferroelectric-paraelectric phase transitions are observed. A qualitative correlation between the temperature dependences of the static dielectric constant and ... |
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| Hopping Transport Equation for Electrons in Superlattices With Vertical Disorder |
23 JUN 2000 |
4 pages |
| Authors:
I. P. Zvyagin; M. A. Ormont; K. E. Borisov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| We develop a theory of vertical hopping transport in doped superlattices with intentional vertical disorder introduced by controlled random variations of well widths. For structures with sufficiently large disorder, the vertical conductance (in the direction of the growth axis) is limited by phonon-assisted hopping between the wells. It is shown that due to quasi-equilibrium situation within the wells, the master rate equation for transitions between the electronic states of the ... |
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| Local Light Polarization Mapping and Electromagnetic Field Imaging by SNOM |
23 JUN 2000 |
3 pages |
| Authors:
A. A. Ejov; D. A. Muzychenko; V. I. Panov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| An influence of the incident light polarization on the aperture probe collection SNOM images have been investigated. Great difference between reflection SNOM images obtained at two orthogonal linear polarizations of the incident light have been observed. The SNOM images of domains and domain walls were studied. Three-dimensional light confinement near small hole in thin metallic film have been mapping by SNOM aperture probe. |
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| Resonant Second-Harmonic Phase Spectroscopy of the Buried Interfaces of Column IV Semiconductors |
23 JUN 2000 |
4 pages |
| Authors:
A. A. Fedyanin; T. V. Dolgova; D. Schuhmacher; G. Marowsky; O. A. Aktsipetrov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| The second-harmonic interferometric spectroscopy (SHIS) is proposed as a new spectroscopic technique to study the resonant electron response of solid state nanostructures. The combination of the second-harmonic (SH) amplitude and phase spectra is shown to be more sensitive to resonant parameters of the electron density of states in comparison with the conventional SH intensity measurements. The resonant anisotropic SH response of buried oxidized Si(111) and Ge(111) surfaces is studied using ... |
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| Optical Properties of Semiconductor (InP)-Dielectric Quantum Wires |
23 JUN 2000 |
4 pages |
| Authors:
K. Chernoutsan; V. Dneprovskii; S. Romanov; O. Shaligina; E. Zhukov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| Virtual-Tunneling-Assisted Vertical Conduction in Superlattices with Intentional Disorder |
18 JUN 1999 |
4 pages |
| Authors:
I. P. Zvyagin; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| A new mechanism of vertical conduction in superlattices with intentional disorder is discussed. We show that at low temperatures the conductance of these structures can be mostly determined by phonon assisted transitions between the second nearest wells in the vicinity of the well with the highest size quantization level. Such transitions involve virtual transitions to The state of the intermediate well and are characterized by a low activation energy and ... |
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| Second Harmonic Generation in Porous Silicon Multilayer Periodic Structures |
18 JUN 1999 |
3 pages |
| Authors:
A. B. Fedotov; L. A. Golovan; P. K. Kashkarov; N. I. Koroteev; M. G. Lisachenko; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| In tne paper second harmonic (SH) generation in a photonic bandgap structure was investigated. The intensity of SH from a multilayer structure exceeds the intensity of SH from both homogeneous layer of porous silicon and a single crystal silicon (100) substrate. The SH generation efficiency was found to be sensitive to parameters of photonic bandgap structures. The dependence of the SH signal on the azimuthal rotation angle is isotropic. SH ... |
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| Optical Second Harmonic Generation Studies of the De-Electric Field Screening in Si-SiO2 Multiple Quantum Wells |
18 JUN 1999 |
6 pages |
| Authors:
V. V. Savkin; A. A. Fedyanin; F. A. Pudonin; A. N. Rubtsov; O. A. Aktsipetrov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| Dc-electric field screening in the Si-SiO2 multiple quantum wells is studied by optical second harmonic generation. Experimentally observed oscillations in the nonlinear response. Inconsistent with semiclassical description of screening, are explained within the Tomas-Fermi approach. |
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| Electronic Superstructures in Doped Semiconductor Superlattices |
JUN 1998 |
4 pages |
| Authors:
I. P. Zuyagin; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| We show that in doped semiconductor superlattices with narrow quantum wells at low temperatures and at sufficiently low doping levels, the exchange-correlation contribution to the system energy can exceed the sum of the kinetic and Hartree energies. Under these conditions, the uniform distribution of electrons over the wells becomes unstable, and the ground state corresponds to inhomogeneous distribution (electronic superstructure). For GaAs/GaAlAs superlattices the estimate of the critical doping concentration ... |
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| Structural and Tunnel Characteristics of Langmuir Films Based on Molecular Cluster Nanostructures |
JUN 1998 |
4 pages |
| Authors:
E. S. Soldatov; S. P. Gubin; V. V. Khanin; G. B. Khomutov; A. Y. Obidenov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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| The approach based on the use of mixed LB films consisted of inert molecular matrix and cluster molecules is effective for formation of reproducible, stable, ordered planar nanostructures with different systems of electron tunnel junctions. The effects of single electron tunneling and/or discrete electronic levels spectrum can be observed and studied in such structures at room temperature. |
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| Excitons in Semiconductor Quantum Wires Crystallized in Transparent Dielectric Matrix |
JUN 1998 |
3 pages |
| Authors:
V. Dneprovskii; T. Kobayashi; E. Mulyarov; S. Tikhodeev; E. Zhukov; MOSCOW STATE UNIV (RUSSIA) DEPT OF PHYSICS
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