Polarization switching to the gain disfavored mode in vertical-cavity surface-emitting lasers

We report on the experimental observation of current-induced polarization switching in vertical-cavity surface-emitting lasers which is accompanied by a decrease of the total output power at the switching point. The relaxation oscillation frequency also decreases. This switching is interpreted as a switching event from the mode with higher (unsaturated) net gain to the gain disfavored mode. The experimental observations are in qualitative agreement with a nonlinear dynamical model taking into account spin degrees of freedom of carriers in a semiconductor quantum well. Within the framework of this model, we propose an explanation for the origin of a minimum in the effective dichroism observed at the switching point, which might also be relevant for other experiments.