We consider two single-mode semiconductor lasers, which are coupled
face to face via the injection of the optical field. We describe
the symmetries of the coupled rate-equations model, the associated
stationary solutions (synchronous and antisynchronous), and the
bifurcations between them for the case when the propagation delay of the injected field is small. For the coupled lasers with a detuning, we discuss the emergence of self-pulsations with specific properties
(anti-phase, in-phase). We also identify parameter regions, where
chaotic pulsations occur.
This paper is concerned with the phenomenon of excitability in semiconductor lasers consisting of a DFB section and a passive dispersive reflector (PDR). We assume that the PDR section contains a Bragg grating and/or a passive Fabry- Perot filter guaranteeing a dispersive reflection of the optical field. We investigate a single mode model for PDR lasers and derive conditions under which excitable behavior can be demonstrated. Especially, we show the existence of a threshold, that is, only perturbations above the threshold imply a large excursion from the steady state, and where the response is almost independent of the strength of the perturbation; moreover we establish the existence of a refractory period, i.e., if a second perturbation is applied before the refractory time has passed, then the system does not respond.