Dynamical regimes in an optically injected semiconductor ring laser

Abstract

We theoretically investigate optical injection in semiconductor ring lasers. Starting from a rate-equation model for semiconductor ring lasers, we use numerical simulations and a bifurcation analysis to reveal all the relevant dynamical regimes that will unfold for different parameter values. Our numerical simulations reproduced the saddle-node and Hopf bifurcation observed in other optically injected laser systems, which typically yield the boundaries of the parameter region in which stable locking can occur. Nevertheless, the bifurcation diagram of the optically injected semiconductor ring laser shows differences with the ones of other semiconductor lasers. For low injection power, we not only observe the regular saddle-node locking bifurcation, we also reveal the presence of an additional family of saddle-node bifurcations and a new Hopf bifurcation. These new bifurcations lead to the coexistence of two injection-locked states in two separate parameter regions and a parameter region is revealed in which a frequency-locked limit cycle coexists with an injection-locked solution, providing an additional route to stable locking. Finally, a chaotic regime that extends to low values of the detuning and injection power is revealed.