Main resonances in directly modulated semiconductor lasers: effect of spontaneous emission and gain saturation

Boundaries for the primary saddle-node bifurcations related to the main resonances in pump-modulated laser diodes are obtained via numerical simulation. The model explicitly contains the gain saturation and spontaneous emission terms and the authors focus on the effect that these terms have on the large signal modulation regime. It is found that the spontaneous emission term strongly modifies the qualitative behaviour of the instability boundaries, while the gain saturation factor manifests itself in the damping of relaxation oscillations and leads to a simple quantitative shift of boundaries.