Instabilities of stationary states in lasers with long-delay optical feedback

We study the Lang-Kobayashi model in the long-delay limit, focussing our attention on the stability properties of external cavity modes (ECMs) of this system. We show that ECMs can display different types of instabilities: strong instabilities and weak modulational-type instability. We explain the origin of these instabilities and show how they affect the complicated dynamics of the Lang-Kobayashi model