Gain switching in high-speed semiconductor lasers: Intermediate-signal analysis

We present a simple analytical treatment of gain switching in semiconductor lasers at intermediate intensities, based on a second-order perturbative treatment of the rate equations. The analytical solution is compared with experimental nonlinear transient relaxation oscillations measured using high-speed, p-doped In0.35Ga0.65As/GaAs multiple quantum well lasers, under perturbation of the dc electrical bias by pulsed optical excitation. The experimental results show excellent agreement with the analytical solution, even at excitation densities beyond the small-signal regime.