Abstract
The effect of gain nonlinearities on the dynamic response is studied using a nonperturbative form of the nonlinear gain in the signal-mode rate equation. The nonperturbative form is different from that used previously and leads to qualitative and quantitative differences in the intensity dependence of the important dynamic parameters such as the frequency and the damping rate for relaxation oscillations. The results are important for the design of high-speed semiconductor lasers and suggest that the new form of the nonlinear gain should be used for modeling the modulation response in both the small-signal and large-signal regimes.