Analysis of gain-switching characteristics including strong gain saturation effects in low-dimensional semiconductor lasers

The effects of gain nonlinearities on gain-switched short-pulse-generation characteristics are analyzed via rate equations assuming a nonlineargain model including a gain saturation parameter gs to quantitatively describe the strong gain-saturation nonlinearity in low-dimensional semiconductor lasers at high carrier densities. It was found that the minimum pulse width and the delay time are mainly determined by g _s rather than a differential gain coefficient g ₀ and a gain compression factor ε. By tracing the temporal evolution of carrier density, photon density, and material gain during gain switching, distinctly different effects of g _s, ε, and cavity lifetime τ _p on pulse generation were clarified.