Chaotic transitions and low-frequency fluctuations in semiconductor laserswith optical feedback

This paper examines the dynamical origin of low-frequency fluctuations (LFF s) in semiconductor lasers subject to time-delayed Lang-Kobayashi equations for a laser pumped near threshold. We construct a bifurcation analysis sch eme that enables the classification of the different operation regimes of t he laser. We use the scheme to study the coexistence of the LFFs and stable emission on the maximum gain mode (MGM), which was the subject of recent e xperiments [T. Hell, I. Fischer, W. Elsasser, Phys. Rev. A 60 (1999) 634]. Our computations suggest that as the feedback level increases, the regime o f sustained LFFs alternates with regions of transient LFFs, where the laser can achieve stabilization on the MGM. Exploration of the parameter space r eveals strong dependence of the structure of the LFF dynamics and the coexi stence regime on the value of the linewidth enhancement factor. (C) 2000 El sevier Science B.V. All rights reserved.