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The evolution of the spatial coherence and the polarization has been studied in a freely decaying polariton condensate that is resonantly excited by linearly polarized picosecond laser pulses at the lower and upper sublevels of the lower polariton branch in a high-Q GaAs-based microcavity with a reduced lateral symmetry without excitation of the exciton reservoir. It is found that the condensate inherits the coherence of the exciting laser pulse at both sublevels in a wide range of excitation densities and retains it for several dozen picoseconds. The linear polarization of the photoexcited condensate is retained only in the condensate at the lower sublevel. The linearly polarized condensate excited at the upper sublevel loses its stability at the excitation densities higher a threshold value: it enters a regime of internal Josephson oscillations with strongly oscillating circular and diagonal linear degrees of polarization. The polariton–polariton interaction leads to the nonlinear Josephson effects at high condensate densities. All the effects are well described in terms of the spinor Gross–Pitaevskii equations. The cause of the polarization instability of the condensate is shown to be the spin anisotropy of the polariton–polariton interaction. 相似文献
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V.E. Bisti V.M. Edelstein I.V. Kukushkin V.D. Kulakovskii 《Solid State Communications》1982,44(2):197-199
The magnetic field dependence of the exciton emission intensity Iex(H) has been investigated in Ge crystals stressed along the direction near 〈100〉. In the low field limit the magnetic field correction has been evaluated to the wave functions of the ground and some excited states of an isotropic exciton. The calculated dependence Iex(H) in the case of Ge is in a good agreement with the experimental one at H ? 0.5 T. 相似文献
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A. A. Maksimov A. V. Pashkov A. S. Brichkin V. D. Kulakovskii I. I. Tartakovskii A. A. Toropov S. V. Ivanov 《Journal of Experimental and Theoretical Physics》2008,106(6):1130-1136
The kinetics and polarized spectra of low-temperature photoluminescence in semiconductor type-II superlattices based on ZnMnSe/ZnSSe structures have been studied in detail. Processes responsible for the formation of short-lived (about 1 ns) and long-lived (above 10 ns) localized exciton-type magnetic polarons (EMPs) in these systems are determined, and the relative contributions due to magnetic and nonmagnetic localization of heavy holes to the formation of such polarons are evaluated. A phenomenological model is constructed that takes into account the energy distribution of charge-carrier traps with respect to their level depths and employs the EMP parameters determined for ZnMnSe quantum wells. Within the proposed model, all spectral, temporal, and temperature-dependent features in the behavior of magnetophotoluminescence observed for the system under consideration can be consistently and quantitatively described. 相似文献
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L. V. Kulik A. I. Tartakovskii A. V. Larionov E. S. Borovitskaya V. D. Kulakovskii 《Journal of Experimental and Theoretical Physics》1997,85(1):195-199
The paper reports on an investigation of changes in the photoluminescence linewidth and lifetime of excitons and electron-hole
plasma over a wide range of densities between 3×107 and 3×1012 cm−2 at a temperature of 77 K in GaAs/AlGaAs quantum wells. The roles played by thermal ionization of excitons at low densities
of nonequilibrium carriers, exciton-exciton and exciton-electron collisions, and ionization of excitons at high pumping power
densities have been studied.
Zh. éksp. Teor. Fiz. 112, 353–361 (July 1997) 相似文献
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Larionov AV Kulakovskii VD Höfling S Schneider C Worschech L Forchel A 《Physical review letters》2010,105(25):256401
The effect of a magnetic field on a spinor exciton-polariton condensate has been investigated. A quenching of a polariton Zeeman splitting and an elliptical polarization of the condensate have been observed at low magnetic fields B<2 T. The effects are attributed to a competition between the magnetic field induced circular polarization buildup and the spin-anisotropic polariton-polariton interaction which favors a linear polarization. The sign of the circular polarization of the condensate emission at B<3 T is negative, suggesting that a dynamic condensation in the excited spin state rather than the ground spin state takes place in this magnetic field range. From about 2T on, the Zeeman splitting opens and from then on the slope of the circular polarization degree changes its sign. For magnetic fields larger than the 3 T, the upper spin state occupation is energetically suppressed and circularly polarized condensation takes place in the ground state. 相似文献
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Theoretical studies are performed of planar cavity–polariton systems under resonant optical excitation. We show that if the cavity is spatially anisotropic, the polariton spin is highly sensitive to the pump polarization direction, which can be used to modulate the circular polarization of the output light. In particular, when the right- and left-circular components of the incident wave have equal intensities and mutually opposite angular momenta, the pump has strictly linear yet angle-dependent polarization and as such brings about a periodic angular variation of the polariton spin. Free motion of polaritons is the other factor determining the shape of the cavity-field distribution. Such externally driven and highly tunable spin patterns represent a counterpart of spin shaping in nonresonantly excited Bose–Einstein condensates of cavity polaritons. 相似文献
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It has been found that interband illumination strongly affects the dynamics of parametric polariton scattering in planar GaAs microcavities under resonant photoexcitation above the inflection point of the polariton dispersion curve: illumination with a power density of about 0.1% of the resonance value reduces the threshold density for the appearance of stimulated scattering by more than 15%. It has been shown that the effect is attributed to a change in the resonance energy of the pumped mode due to an increase in the density of long-lived exciton-like polaritons formed owing to the scattering of resonantly-excited polaritons on photoexcited free carriers. 相似文献
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S. V. Zaitsev V. D. Kulakovskii A. A. Maksimov D. A. Pronin I. I. Tartakovskii N. A. Gippius M. Th. Litz F. Fisher A. Waag D. R. Yakovlev W. Ossau G. Landwehr 《JETP Letters》1997,66(5):376-381
A giant blue shift (≈0.5 eV) and a large decrease in the emission time of a spectral band corresponding to radiative recombination
of spatially separated electrons and holes are observed in ZnSe/BeTe superlattices at high laser excitation levels. On the
basis of numerical calculations, the observed defects are attributed to band bending arising in type-II structures at high
carrier density.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 5, 351–356 (10 September 1997) 相似文献
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M. G. Tyazhlov A. I. Filin A. V. Larionov V. D. Kulakovskii D. R. Yakovlev A. Waag G. Landwehr 《Journal of Experimental and Theoretical Physics》1997,85(4):784-796
Spin relaxation of Mn ions in a Cd0.97Mn0.03Te/Cd0.75Mg0.25Te quantum well with photogenerated quasi-two-dimensional electron-hole plasma at liquid helium temperatures in an external
magnetic field has been investigated. Heating of Mn ions by photogenerated carriers due to spin and energy exchange between
the hot electron-hole plasma and Mn ions through direct sd-interaction between electron and Mn spins has been detected. This process has a short characteristic time of about 4 ns,
which leads to appreciable heating of the Mn spin subsystem in about 0.5 ns. Even under uniform excitation of a dense electron-hole
plasma, the Mn heating is spatially nonuniform, and leads to formation of spin domains in the quantum well magnetic subsystem.
The relaxation time of spin domains after pulsed excitation is measured to be about 70 ns. Energy relaxation of excitons in
the random exchange potential due to spin domains results from exciton diffusion in magnetic field B=14 T with a characteristic time of 1 to 4 ns. The relaxation time decreases with decreasing optical pump power, which indicates
smaller dimensions of spin domains. In weak magnetic fields (B=2 T) a slow down in the exciton diffusion to 15 ns has been detected. This slow down is due to exciton binding to neutral
donors (formation of bound excitons) and smaller spin domain amplitudes in low magnetic fields. The optically determined spin-lattice
relaxation time of Mn ions in a magnetic field of 14 T is 270±10 and 16±7 ns for Mn concentrations of 3% and 12%, respectively.
Zh. éksp. Teor. Fiz. 112, 1440–1463 (October 1997) 相似文献