Near- and mid-infrared spectroscopy of InGaAs/GaAs quantum dot structures

Results of a photoluminescence and electroluminescence study of vertically coupled In0.5Ga0.5As/GaAs quantum dot?(QD) structures with an extended waveguide (1.24??m thick) are presented. Spectra of spontaneous and stimulated near-infrared (?1??m) emission as well as spectra of spontaneous mid-infrared?(MIR) (?12??m) emission are obtained under optical and electrical pumping. It is shown that the observed MIR emission is connected with intraband electron optical transitions in the QD structures.