Aspects of Feedback and Noise in Vertical-Cavity Surface-Emitting Lasers

The dynamics of Vertical-Cavity Surface-Emitting Lasers (VCSELs) are
affected by the presence of external perturbations. As most semiconductor
lasers, VCSELs exhibit an interesting dynamical behavior that is further
enriched by the polarization degree of freedom, due to the cylindrical
symmetry of these devices. Here, we study the influence of external
current noise and external optical feedback on the dynamical properties of
VCSELs, including the relaxation oscillation dynamics, polarization mode
dynamics and delay induced instabilities. The consideration of noise, both in experiments and modelling, is of critical importance for the understanding of semiconductor lasers. According to our results, current noise has an ambivalent character since noise has a damping effect on the relaxation oscillation dynamics but a destabilizing effect in some types of feedback-induced dynamics.