Dynamics of delay-coupled semiconductor laser systems
Nonlinear laser dynamics has received considerable attention because of possible applications, but also fundamental physical and mathematical aspects are of great interest. This thesis is concerned with the dynamical behavior of semiconductor lasers subject to external delayed perturbations. In particular the time delay in the coupling to external elements is of importance, because it substantially complicates the dynamical behavior. This time delay arises from finite signal propagation times and, hence, is large compared to the laser internal time scales so that it cannot be neglected. Specifically, the thesis investigates two different delay-coupled semiconductor laser systems: (I) a semiconductor laser subject to delayed filtered optical feedback, where a part of the laser emission is filtered by a Fabry-Perot filter and then feed back into the laser, and (II) two semiconductor lasers that are mutually delay-coupled via their optical fields. With concepts and tools from dynamical systems theory a comprehensive study of the underlying bifurcation structure of two systems is presented. Knowledge of this underlying structure is the key to understanding complicated laser dynamics. The results from the bifurcation analysis are interpreted in terms of the dynamics of the real laser system and compared with experiments.