| Semiconductor lasers are widely used in a diversity of applications, yet many of their characteristics are not completely understood. In this thesis some properties of the semiconductor laser with optical injection and with optical feedback are investigated.; Light injected into a semiconductor laser can completely alter the laser's dynamical characteristics. In a regime with weak optical injection the laser output may exhibit bistability and hysteresis. This system is of great interest due to its applicability as a switching device. An analytical, numerical, and experimental study of dynamical hysteresis as a function of the switching parameter is performed. It is found that the extent of hysteresis depends on the amplitude and frequency of the switching parameter itself. Scaling laws, which describe the growth of the hysteresis loop area, are obtained in the limit of low switching frequencies.; A semiconductor laser with external optical feedback may exhibit abrupt power dropout events. During a power dropout event the laser intensity suddenly drops to almost zero and the intensity is built-up in a stepwise fashion. Previous studies attributed the occurrence of dropout events to either solely deterministic mechanisms or to stochastic mechanisms. Numerical simulations of the laser equations including and omitting noise show, that in some parameter regimes, noise has a significant influence on the dropout statistics. Experimental measurements of the statistical distribution of the time intervals between dropout events as a function of the feedback strength indicate that noise is instrumental in inducing the dropout events in the regime investigated here. |
