Dynamical behavior of a semiconductor laser with filtered external opticalfeedback

We report on a theoretical analysis of the dynamical performance of a semic onductor laser under the influence of delayed weak filtered external optica l feedback. The filter widths considered range from 1 to 100 GHz. The analy sis concentrates on the well-known low-frequency fluctuations (LFF's) regim e, in which LFF's occur in the absence of filtering. As expected, filtering the feedback light stabilizes the system in general. LFF can already be su ppressed for moderately broad filters (25-50 GHz). In that case, the system was found to operate on the maximum gain mode with a small amplitude limit cycle. We show how the filtering can, in principle, be used for targeting the laser on the maximum gain mode.