  Simultaneous two-state lasing is a unique property of semiconductor
quantum-dot (QD) lasers. This not only changes steady-state characteristics of
the laser device but also its dynamic response to perturbations. In this paper
we investigate the dynamic stability of QD lasers in an external optical
injection setup. Compared to conventional single-state laser devices, we find a
strong suppression of dynamical instabilities in two-state lasers. Furthermore,
depending on the frequency and intensity of the injected light, pronounced
areas of bistability between both lasing frequencies appear, which can be
employed for fast optical switching in all-optical photonic computing
applications. These results emphasize the suitability of QD semiconductor
lasers in future integrated optoelectronic systems where a high level of
stability is required.
