Spontaneous IR intersublevel emission from quantum dots conditioned by main interband lasing

Abstract

The physical mechanism for creation of intraband population inversion between levels of quantum dots under injection of electron-hole pairs of suggested. The method is based on employment of generation of interband radiation providing fast depopulation of quantum dot ground level. Spontaneous far-IR radiation from diode laser structures with InGaAs/AlGaAs quantum dots connected with intraband hole and/or electron transitions between levels of size quantization in quantum dots was found and investigated for the first time. Spontaneous far-IR radiation is observed only under simultaneous generation of stimulated near-IR radiation connected with interband carrier transitions. Far- IR emission is observed also from laser structures with InGaAs/GaAs quantum wells. Intensity of this radiation is about of order less then intensity of radiation from structures with quantum dots. Qualitative explanations of phenomena observed are proposed.