Thermal effects and transverse structures in semiconductor microcavities with population inversion

We formulate a model that includes the thermal dynamics in the time evolution of a semiconductor multiple quantum-well microresonator, driven by a coherent holding beam. This model is analyzed in the case in which the active layer is electrically pumped, in such a way that the device behaves like an amplifier, but, in absence of the external beam, does not lase. The inclusion of thermal effects introduces a Hopf instability, which, in certain regions of the parameter space, dominates the behavior of the system. In this case our numerical simulations in one transverse dimension, both with periodic boundary conditions and with a spatially confined current, show that spatial patterns and cavity solitons perform a drift motion in the transverse direction. This motion develops over the slow time scale which characterizes thermal effects. We show that, by applying an appropriate phase modulation one can neutralize this effect and stabilize a cavity soliton around an equilibrium position. For larger values of the driving field intensity one meets the phenomenon of spontaneous formation of cavity solitons by thermal activation, without use of a writing beam, in accord with experimental observations.