Gain Studies on Quantum-Dot Lasers With Temperature-Stable Emission Wavelength

In this paper, a comparative study of the gain spectra of quantum-well (QW) and quantum-dot (QD) lasers is presented. We point out the differences between the gain function of a QD laser and a QW laser and give a qualitative description of the effect that leads to the high wavelength stability of QD lasers. Furthermore, we demonstrate, by means of the gain spectra of an InGaAs and AlInGaAs QD laser, that devices with a high wavelength stability can be manufactured over a wide range of emission energies. The experimentally obtained data are fitted with a theoretical model that describes the gain of a QD ensemble. The characteristic features resulting in the high wavelength stability of QD lasers of 0.072 nm/K are analyzed and discussed.