A manifestation of the magnetopolaron effect in reflection and absorption of light by a three-level system in a quantum well

Abstract

The light absorption A and reflection R coefficients for a three-level system in a quantum well (QW) in a strong magnetic field H, directed perpendicularly to the QW's plane, have been calculated. The energy levels correspond to the ground state and to magnetopolaron energy levelshω 1(2) with the inverse lifetimes γ r1(2) and γ 1(2) . The inverse radiative lifetime of an EHP γ rξ (K ⊥ ) = 0 only under condition K ⊥ ≤ ω ξ n/c, wherehω ξ is the EHP energy. It has been shown that γ rξ (K ⊥ ) is proportional to H. The values γra(K ⊥ ) and γ rb (K ⊥ ) 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 Hres = mecωLO/|e| γ res ra = γ res rb = γ res rξ 0 /2, where the index ξ0 corresponds to the EHP with ne = n h = 1. γra and γ rb are strongly dependent on H − Hres. A numerical estimate for GaAs is: γ res rξ 0 = γ0 = 5.35 · 10 −5 eV. The dependencies A(H) and 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 Hres for the combined polaron case depends on a QW's depth and width.

Elastic light scattering by semiconductor quantum dots of arbitrary shape

“…It is well known (see, for example, [1][2][3][4][5][6][7][8]) that the exact account of the electron-electromagnetic field interaction and account of the exciton nonradiative broadening γ η results in the replacement of the factor (ω l − ω η + iδ) (11), where γ rη is the radiative broadening,hω η is the renormalized exciton energy,ω η = ω η + ∆ω η .…”

“…Let us emphasize that calculations of current and charge densities are made in view of exciton nonradiative broadenings γ [5], that allows to calculate not only scattering, but the light absorption also (at γ = 0 the light absorption is absent). The quasi-classical method in calculations of reflection and absorption coefficients in quantum wells was used in [4,[6][7][8]. In [9] the same method was applied to calculation of electric fields arising at resonant light scattering on excitons Γ 6 × Γ 7 in spherical quantum dots, consisting of crystals of a class T d (for example, GaAs) and limited by an infinitely high potential barrier.…”

“…For quantum wells this task is solved in [6][7][8]. In [9] γ = 0, and the light absorption by a quantum dot is absent.…”

Effect of the anomalous dispersion on the optical characteristics of a quantum well

“…In this case, it is impossible to be limited by linear approximation on interaction of electrons with electromagnetic field, and it is necessary to consider all the orders of this interaction 5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24 . Reflection, absorption and transmission of an electromagnetic wave, which interacts with discrete energy levels of electronic system in a quantum well in the region of frequencies corresponding to interband transitions, were considered in 13,14,15,16,17,18,19 . In these works, a stimulating light could be monochromatic 19 or pulse irradiation 13,14,15 .…”

“…Reflection, absorption and transmission of an electromagnetic wave, which interacts with discrete energy levels of electronic system in a quantum well in the region of frequencies corresponding to interband transitions, were considered in 13,14,15,16,17,18,19 . In these works, a stimulating light could be monochromatic 19 or pulse irradiation 13,14,15 . One 16 , two 17,19 and large number of excited energy levels 18 were considered.…”