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. Our model contains explicitly the gain saturation and
spontaneous emission terms and we focus on the effect that these terms have on the large signal modulation regime. We find that the spontaneous emission term strongly modifies the qualitative behavior of the
instabilities boundaries, while the gain saturation
factor manifests itself in the damping of relaxation oscillations and
leads to a simple quantitative shift of boundaries.