A5035036906- Semiconductor Quantum Structures and Devices
- Quantum and electron transport phenomena
- Strong Light-Matter Interactions
- Spectroscopy and Quantum Chemical Studies
- Gamma-ray bursts and supernovae
- Spectroscopy and Laser Applications
- Semiconductor Lasers and Optical Devices
- Astrophysics and Cosmic Phenomena
- Quantum optics and atomic interactions
- SAS software applications and methods
- Semiconductor materials and devices
- Physics of Superconductivity and Magnetism
- Photonic and Optical Devices
- Magnetic properties of thin films
- Astronomy and Astrophysical Research
- Terahertz technology and applications
- Thermal Radiation and Cooling Technologies
- Advanced Semiconductor Detectors and Materials
- Ion-surface interactions and analysis
- Quantum Dots Synthesis And Properties
- Atmospheric Ozone and Climate
- Radio Astronomy Observations and Technology
- Astro and Planetary Science
- Random lasers and scattering media
- Astronomical Observations and Instrumentation
St Petersburg University
2015-2024
Nanophoton (Brazil)
2023
Moscow Institute of Physics and Technology
2018
Saint Peter's University
2017
Crimean Astrophysical Observatory
1995-2013
Institute of Physics
2001-2007
Physico-Technical Institute
2006-2007
Russian Academy of Sciences
2006-2007
University of Bath
2006
Special Astrophysical Observatory
2005
We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to September 2009, for total 76 GRBs, and present an additional three pre-Swift not included in earlier sample. Furthermore, we publish 840 new points 42 GRB afterglows, sets 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A 080810. analyzed light curves all derived spectral energy distributions with best quality, allowing us estimate host...
(Abridged) OJ287 is a BL Lac object that has shown double-peaked bursts at regular intervals of ~12 yr during the last ~40 yr. We analyse optical photopolarimetric monitoring data from 2005-2009, which latest outburst occurred. The aim this study twofold: firstly, we to variability patterns and statistical properties polarization light-curve. find strong preferred position angle in polarization. can be explained by separating jet emission into two components: an core chaotic emission. stable...
Spin-relaxation times of two-dimensional electrons in asymmetrical (001) AlGaAs quantum wells are measured by means Hanle effect. Three different spin-relaxation for spins oriented along [110], $[1\overline{1}0]$, and [001] crystallographic directions extracted demonstrating anisotropy the D'yakonov-Perel' spin relaxation mechanism. The relative strengths Rashba Dresselhaus terms describing spin-orbit coupling semiconductor well structures obtained. It is shown that splitting about four...
Context. The international whole earth blazar telescope (WEBT) consortium planned and carried out three days of intensive micro-variability observations S5 0716+714 from February 22, 2009 to 25, 2009. This object was chosen due its bright apparent magnitude range, high declination, very large duty cycle for micro-variations. Aims. We report here on the long continuous optical light curve obtained during multi-site observing campaign which Blazar showed almost constant variability over a 0.5...
The binding energy and the corresponding wave function of excitons in GaAs-based finite square quantum wells (QWs) are calculated by direct numerical solution three-dimensional Schrödinger equation. precise results for lowest exciton state obtained Hamiltonian discretization using high-order finite-difference scheme. microscopic calculations compared with standard variational approach. energies found two methods coincide within 0.1 meV wide range QW widths. radiative decay rate is QWs...
Photoluminescence and reflectivity spectra of a high-quality InGaAs/GaAs quantum well structure reveal series ultranarrow peaks attributed to the confined exciton states. The intensity these decreases as function temperature, while linewidths demonstrate complex peculiar behavior. At low pumping widths all remain quite narrow $(<0.1\phantom{\rule{0.28em}{0ex}}\mathrm{meV})$ in whole temperature range studied, 4--30 K. stronger pumping, linewidth first increases then drops down with rise....
Abstract Rapid development of spin noise spectroscopy the last decade has led to a number remarkable achievements in fields both magnetic resonance and optical spectroscopy. In this report, we demonstrate new – magnetometric potential use it study acting upon electron spin-system an n -GaAs layer high-Q microcavity probed by elliptically polarized light. Along with external field, applied sample, spectrum revealed Overhauser field created optically oriented nuclei additional, previously...
We present intensive optical, infrared, and radio monitoring observations of the BL Lac object OJ 287, taken between years 1993-1998. Two large optical outbursts were detected at predicted times in November 1994 December 1995. The detection these supports binary black hole model for 287. Optical polarisation show variability degree position angle, very similar to those observed during 1983/84 outburst angles behaviour observations, indicating that, least, magnetic field orientations bands...
We present results of imaging and aperture polarimetry the dust comet 2P/Encke at phase angles 91–105°, obtained during 2003 apparition. investigate how strongly molecular emissions transmitted by filters used in observations can affect resulting polarization cometary dust. This problem is particular importance for so-called gas-rich comets like which has particularly strong emission as compared to its continuum. Aperture wide-band UBVR was performed 2.6-m Shain telescope 1.25-m Crimean...
We report a remarkable enhancement of the magnetic moments excitons as result their motion. This surprising result, which we have observed in magneto-optical studies three distinct zinc-blende semiconductors, GaAs, CdTe, and ZnSe, becomes significant kinetic energy exciton comparable with its Rydberg is attributed to motionally induced changes internal structure exciton. The moment function translational wave vector can be represented by universal equation.
Optical spectroscopy of resonant reflection has been used for both experimental and theoretical studies the exciton-light interaction in wide, high-quality quantum-well structures with widths exceeding exciton Bohr radius by an order magnitude or more. The light mixes low-lying confined states which are captured generalized model developed M. Voronov et al. [Phys. Solid State 49, 1792 (2007)]. We demonstrate that high-energy wide QWs can still be described standard amplitude coefficient from...
We report on the experimental evidence for a nanosecond timescale spin memory based nonradiative excitons with large in-plane wave vector. The effect manifests itself in magnetic-field-induced oscillations of energy optically active (radiative) excitons. detected by spectrally resolved pump-probe technique applied to GaAs/AlGaAs quantum well structure transverse magnetic field persist over timescale, which is orders magnitude longer than characteristic decoherence time system. attributed...
Zeeman splitting of quantum-confined states excitons in InGaAs quantum wells (QWs) is experimentally found to depend strongly on quantization energy. Moreover, it changes sign when the energy increases with a decrease QW width. In 87-nm QW, change observed for excited states, which are above ground state only by few meV. A two-step approach numerical solution two-particle Schr\"odinger equation, taking into account Coulomb interaction and valence-band coupling, used theoretical justification...
The dynamics of electron-spin coherence in $\mathrm{GaAs}∕{\mathrm{Al}}_{0.34}{\mathrm{Ga}}_{0.66}\mathrm{As}$ quantum wells has been studied experimentally by a pump-probe Kerr rotation technique. dephasing time was measured to be $10\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ for 17-nm well containing about ${10}^{10}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}2}$ background electrons at temperature $1.8\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Decrease the electron density causes...
We propose a method of spatial modulation inhomogeneous broadening quantum-well excitonic resonance based on local generation defects produced by focused ion beam. The is applied to fabrication diffraction grating in single InGaAs/GaAs structure irradiating the sample with beam 35-keV He+ ions exposure doses <1012 cm-2. spectrum resonant such narrower than that reflectivity and decreases much faster increasing temperature. A proposed model formation diffractive response scattering...
We present an experimental and theoretical study of the lowest exciton states in a 30-nm single GaAs quantum-well heterostructure different electric fields. found that excitons quantum wells are highly sensitive to field demonstrate nonlinear behavior terms their energy position, amplitude, spectral width, phase resonances reflection spectra. Comparison results with calculations allowed us reliably determine strength layer.
The effect of irradiation by 30‐keV Ga + and 35‐keV He ions (in relatively small doses) on the excitonic reflectivity spectra single InGaAs/GaAs quantum‐well structures is studied. It found that results in decreasing intensity broadening resonances for all doses. shown these changes are not related to a decrease exciton transition oscillator strength and, therefore, irradiation‐induced destruction states, but can be rather ascribed common cause, namely, inhomogeneous proportional exposure...
Multiple frequency quantum beats of a system the coherently excited confined exciton states in high-quality semiconductor structure containing wide InGaAs/GaAs well are experimentally detected by spectrally resolved pump-probe method. The beat signal is observed both at positive and negative delays between pump probe pulses. Several (QB) frequencies experiments, which coincide with interlevel spacings system. A theoretical model developed, allows one to attribute QBs delay four-wave mixing...
In this work we have investigated the exciton reflectance spectra of a high quality heterostructure with GaAs/AlGaAs quantum well in transverse magnetic field (Voigt geometry). It has been shown that application leads to decrease energy distance between spectral features related excitonlike polariton modes. This effect treated as magneto-induced increase mass. We hydrogenlike and diamagnetic models are insufficient describe behavior intermediate fields studied. Considering symmetry problem,...
Picosecond kinetics of polarized resonant photoluminescence (PL) HH excitons in the GaAs/AlGaAs superlattices is studied an external magnetic field. The measurements were made real time using a streak camera. For field aligned along heterostructure growth direction, PL exhibits oscillations degree linear polarization. are ascribed to quantum beats between sublevels optically active excitonic doublet split by plane layers, found exhibit circular These related states and inactive doublets....
The effect of external electric bias on the kinetics circularly polarized photoluminescence (PL) GaAs quantum wells (QWs) is studied experimentally. It found that a negative applied to top surface samples causes appearance slow component in decay PL circular polarization. amplitude this grows with ${U}_{\mathrm{bias}}$ and reaches nearly 100% at ${U}_{\mathrm{bias}}=\ensuremath{-}2\mathrm{V}.$ In transverse magnetic field, polarization shows oscillations related spin precession. changes...
We report on the observation of a significant increase radiative decay rates for exciton transitions in wide (In,Ga)As/GaAs quantum well ($L=95$ nm) magnetic fields up to 6 T applied along growth axis heterostructure. The absolute values are obtained from quantitative analysis resonant features experimentally measured reflectance spectra range optical quantum-confined states. High crystalline quality heterostructure allows us observe ground and several excited with nonradiative broadening...