Nonlinear gain and carrier temperature dynamics in semiconductor laser media

The macroscopic behavior of a semiconductor laser medium is described by use of modified rate equations. The model, valid on time scales greater than 10-13 s, explicitly treats carrier temperature as a dynamic variable and includes the nonlinear dependence of the gain function on carrier density and temperature. Gain suppression that is due to carrier heating is a natural consequence of the model and gives a qualitative explanation of subpicosecond gain dynamics experiments without introducing gain nonlinearity phenomenologically. We demonstrate the temperature behavior of the laser during transient dynamics near and well above threshold. By including carrier temperature as a dynamic variable we show that the laser response to an external perturbation exhibits a noticeable change in the damped oscillations of the photon density compared with that in models without temperature dynamics. Variation in the evolution of the gain function for different external pulse energies is also demonstrated.