Many-body effects and self-contained phase dynamics in an optically injected quantum-dot laser

Quantum-dot (QD) lasers exhibit unique properties when subjected to optical injection, e.g. lower sensitivity and less complex dynamics when compared to conventional quantum-well (QW) lasers. These features can be explained by a lower phase-amplitude coupling and a higher damping of relaxation oscillations in QD laser devices. In this work, we investigate an optically injected QD laser and clarify the role of many-body effects. We model the QD laser device using a semi-classical approach based on the semiconductor-Bloch and Maxwell's equations. The QD optical transition is modeled with a finite spectral width, accounting for inhomogeneous broadening due to QD imperfections. Furthermore, many-body Coulomb interactions, leading to renormalizations of the single-particle energies, are taken into account assuming the screened Hartree-Fock approximation. Throughout the literature the phase dynamics of the electric field inside the laser cavity is implemented by assuming a constant α-factor. Our model accounts for the effects of α via a more rigorous treatment of light-semiconductor interaction. As a result the model allows to extract a value for the α-factor from the intrinsic phase dynamics of the system. The extracted α-factor is not a constant, but rather changes on the one hand dynamically throughout the simulations, and on the other hand with all operation conditions. Furthermore, the dynamical shift of the band-gap energy due to the Coulomb interactions gives rise to modifications in the locking behavior of the laser, that can not be explained with the simpler free-carrier models. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).