Composite-cavity and delayed feedback semiconductor laser instabilities.

This dissertation studies instabilities in semiconductor lasers with external feedback using two distinct models. The first model considers composite-cavity modes and assumes a perfectly reflecting external mirror. It is found that tiny displacements of the external mirror cause an instability which results in a mode-hopping phenomenon. These displacements induce relaxation oscillations in the laser output which might be interpreted as chaos. The second model assumes delayed feedback from a distant reflector. The delay-differential equations that typically describe this model are reduced to a two-dimensional map model that shows intermittency in the transition to chaos. The map is generalized to a multidimensional model. The generalized mapping exhibits chaotic pulsations and a collapse to equilibrium which are reminiscent of feedback experiments