Optical gain in GaAs doping superlattices

The first optical gain measurements have been performed on GaAs doping superlattices grown by molecular beam epitaxy. A maximum gain of 300 cm−1 is obtained in the layered material at a photon energy of 1.35 eV using an excitation density of only 20 W cm−2. Due to the unique tunable energy gap of doping superlattices, the stimulated emission occurs at photon energies far below the gap of bulk GaAs and can be shifted by appropriate choice of the excitation density. Thus, a strong shift of the energetic position of the gain spectra to 1.40 eV with an increased gain of 400 cm−1 is observed when the excitation density is increased to 500 W cm−2.