Modulational instabilities and cavity solitons in semiconductor microcavities

We consider a model recently proposed, describing a multiple quantum well semiconductor microcavity driven by a coherent holding beam. We discuss here some general features of stationary modulational instabilities affecting the system. By generalizing a method introduced in a previous paper on two-level atoms in optical cavities, we give a detailed description of the stationary instabilities in the parameter space. The modulational instability can be related to the presence of stable cavity solitons, which have been predicted in this system. Therefore we have a helpful tool to research the best parametric conditions for stable cavity solitons, a very demanding task due to the large number of parameters. Finally, we show that our analysis can be extended to more general models, describing a nonlinear diffusive material inside an optical cavity with a general form of the interaction terms.