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

Abstract

The absorption and reflection of light by a quantum well are investigated in the case of two closely spaced levels of electronic excitations in the well. The dependences of the dimensionless absorptance Open image in new window and reflectance ℛ on the frequency ωl of the exciting light are calculated. The overall sequence of processes involving absorption and reemission of photons is taken into account. This is beyond the scope of the perturbation theory for the photon-electron coupling constant. It is shown that the perturbation theory is inapplicable when the reciprocal radiative lifetimes of excitations are comparable to the reciprocal nonradiative lifetimes. In this case, the nontrivial dependences Open image in new window and ℛ(ωl) are obtained. The total reflection and the total transparency points are determined. The relationships derived are used to analyze the special case of two excitation levels that are formed in the quantum well in a strong magnetic field H normal to its plane due to the Johnson-Larsen magnetopolaron effect. The reciprocal radiative lifetimes of electron-hole pairs are calculated far from and in the vicinity of the magnetophonon resonance. It is found that these lifetimes are proportional to H in the range far from the resonance and depend strongly on the difference H-Hres in the vicinity of the resonance. The dependences of the coefficients Open image in new window and ℛ on the magnetic field H at different frequencies of the exciting light are deduced.