Gain characteristics of InAs/GaAs self-organized quantum-dot lasers

We report a study of the gain characteristics of a self-organized InAs/GaAs quantum-dot laser. Using the Hakki-Paoli technique, we are able to determi ne the spectral form of the modal gain, its dependence upon current, and th e differential gain. A quasiperiodic modulation of the below-threshold gain is observed. This modulation is shown to be responsible for the form of th e lasing spectra, which consist of groups of lasing modes separated by nonl asing spectral regions. Possible mechanisms for this behavior are discussed . (C) 1999 American Institute of Physics. [S0003-6951(99)01548-X].