Regular dynamics of low-frequency fluctuations in external cavity semiconductor lasers - art. no. 056206

It is commonly believed that the dynamics responsible for low-frequency flu ctuations (LFF's) in external cavity semiconductor lasers is stochastic or chaotic. A common approach to address the origin of LFF's is to investigate the dynamical behavior of, and the interaction among, various external cav ity modes in the Lang-Kobayashi (LK) paradigm. In this paper, we propose a framework for understanding of the LFFs based on a different set of fundame ntal solutions of the LK equations, which are periodic or quasiperiodic, an d which are characterized by a sequence of time-locked pulses with slowly v arying magnitude. We present numerical evidence and heuristic arguments, in dicating that the dynamics of LFF's emerges as a result of quasiperiodic bi furcations from these solutions as the pumping current increases. Regular p eriodic solutions can actually be observed when (1) the feedback level is m oderate, (2) pumping current is below solitary threshold, and (3) the linew idth enhancement factor is relatively large.