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S. T. Pavlov

Publications and source records attributed to S. T. Pavlov.

26 records · Page 2Linked to original sources
arXiv2001

A Role of a Spatial Dispersion of an Electromagnetic Wave Coming Through a Quantum Well

A theory of light transmission through a quantum well (QW) in a magnetic field perpendicular to the QW plane is developed. The light wave length is supposed comparable with the QW width. The formulas for reflection, absorption and transmission take into account the spatial dispersion of the light monochromatic wave and a difference of the refraction indexes of the QW and barrier. We suppose a normal light incidence on the QW plane and consider only one excited energy level. These two factors influence mostly light reflection, since an additional reflection from the QW borders appears to the reflection due to interband transitions in the QW. The most radical changes in reflection appear when a radiative broadening of the excited energy level is small in comparison to a nonradiative broadening. Our theory is limited by the condition of existence of size-quantized energy levels which is satisfied for quite narrow QW's.

cond-mat.mes-hall↗
arXiv2000

Reflection and absorption of QWs irradiated by light pulses in a strong magnetic field

It has been shown that the non-sinusoidal character oscillations appear in the transmitted, reflected and absorbed light fluxes when light pulses irradiate a semiconductor quantum well (QW), containing a set of a large number of the equidistant energy levels of electronic excitations. The oscillation amplitude is comparable to the flux values for the short pulses, duration of which γ_l^{-1} \leq \hbar/ΔE. A damping echo of the exciting pulse appears through the time intervals 2π\hbar/ΔE in the case of the very short light pulses γ_l^{-1}\ll \hbar/ΔE. Symmetrical and asymmetrical pulses with a sharp front have been considered. Our theory is applicable for the narrow QWs in a strong magnetic field, when the equidistant energy levels correspond to the electron-hole pairs with different Landau quantum numbers.

cond-mat.mes-hall↗
arXiv2000

Magnetopolaron effects in light reflection and absorption of a three-level system in a QW

The light absorption {\cal A} and reflection{\calR} coefficients for a three-level system in a quantum well (QW) in a strong magnetic field {\bf H}, directed perpendicularly to the QW's plane, have been calculated. The energy levels correspond to the ground state and to magnetopolaron energy levels \hbarω_{1(2)} with the inverse lifetimes γ_{r1(2)} and γ_{1(2)}. The inverse radiative lifetime of an EHP in a QW γ_{rξ}(\bf{\cal K}_{\perp})\not=0 only under condition {\cal K}_{\perp}\leω_ξn/c, where \hbarω_ξis the EHP energy. It has been shown that γ_{rξ}(\bf{\cal K}_{\perp}) is proportional to H. The values γ_{ra}(\bf{\cal K}_{\perp}) and γ_{rb}(\bf{\cal K}_{\perp}) for an excitation consisting of a hole and a usual magnetopolaron have been calculated. The index a(b) designates a magnetopolaron upper (lower) term. In the resonance at H_{res}=m_ecω_{LO}/|e|~~ γ_{ra}^{res}=γ_{rb}^{res}=γ_{rξ_0}^{res}/2, where the index ξ_0 corresponds to the EHP with n_e=n_h=1. The dependencies {\cal A}(H)$ and ${\cal R}(H) for various values of ω_l in the magnetophonon resonance vicinity have been obtained. The existence of "combined"and "weak" polarons has been predicted. The resonant value H_{res} for the combined polaron case depends on a QW's depth and width.

cond-mat.mes-hall↗
arXiv2000

Magnetooptical effects in quantum wells irradiated with light pulses

The method of detection and investigation of the magnetopolaron effect in the semiconductor quantum wells (QW) in a strong magnetic field, based on pulse light irradiation and measuring the reflected and transmitted pulses, has been proposed. It has been shown that a beating amplitude on the frequencies, corresponding to the magnetopolaron energy level splitting, depends strongly from the exciting pulse width. The existence of the time points of the total reflection and total transparency has been predicted. The high orders of the perturbation theory on electron-electromagnetic field interaction have been taken into account.

cond-mat.mes-hall↗
arXiv2000

Profile alterations of a symmetrical light pulse coming through a quantum well

The theory of a response of a two-energy-level system, irradiated by symmetrical light pulses, has been developed.(Suchlike electronic system approximates under the definite conditions a single ideal quantum well (QW) in a strong magnetic field {\bf H}, directed perpendicularly to the QW's plane, or in magnetic field absence.) The general formulae for the time-dependence of non-dimensional reflection {\cal R}(t), absorption {\cal A}(t) and transmission {\cal T}(t) of a symmetrical light pulse have been obtained. It has been shown that the singularities of three types exist on the dependencies {\cal R}(t), {\cal A}(t), {\cal T}(t). The oscillating time dependence of {\cal R}(t), {\cal A}(t), {\cal T}(t) on the detuning frequency Δω=ω_l-ω_0 takes place. The oscillations are more easily observable when Δω\simeqγ_l. The positions of the total absorption, reflection and transparency singularities are examined when the frequency ω_l is detuned.

cond-mat.mes-hall↗
arXiv1996

Magnetic Field-Induced Fano Profiles in the Absorption Coefficient of Semiconductors

A strongly asymmetric, Fano-like resonance profile has been found for magneto-absorption in the states of hot free electron-hole pairs scattered by defects in bulk semiconductors. The renormalization of the absorption profile, compared to that expected from the bare density of states in a high magnetic field, follows from a quasi-one-dimensional character of electronic excitations. The results are valid for absorption by the electronic states of large Landau quantum number where the Coulomb interaction should play a minor role. The resonance shape is in a good qualitattive agreement with experimental observations.

cond-mat↗
arXiv1996

Magnetic-field-enhanced outgoing excitonic resonance in multi-phonon Raman scattering from polar semiconductors

A combined scattering mechanism involving the states of free electron-hole pairs (exciton continuum) and discrete excitons as intermediate states in the multi-phonon Raman scattering leads to (1) a strong increase of the scattering efficiency in the presence of a high magnetic field and to (2) an outgoing excitonic resonance: the two features are not compatible when only free pairs (leading to a strong increase of the scattering efficiency under the applied magnetic field) or discrete excitons (resulting in the outgoing resonance at the excitonic gap) are taken into account.

cond-mat↗