Quantum Dot Samples under Low Level of Electronic Excitation

The paper refers to the experimentally observed emission of quantum dot lasers from higher excited states and to the closely related experiments on the emission of quantum dot samples from higher excited states and the effects of up-conversion of electronic level occupation. The attention is paid to certain experiments in which the dependence of the up-conversion effect on the intensity of the optical excitation is sometimes observed even at low levels of electronic excitation. The theoretical interpretation of the effect is given here within the frame of the multiple scattering of quantum dot electrons on longitudinal optical phonons of polar semiconductor materials