Influence of amplitude-phase coupling on the dynamics of semiconductor lasers subject to optical feedback

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Abstract
We present extensive experimental investigations of the dynamics of semiconductor lasers subject to optical feedback in dependence on the linewidth enhancement factor α which accounts for the amplitude phase coupling of the optical field. A reduction of α leads to conspicuous changes of the dynamics of the system which are characterized and classified in the phase space of feedback strength versus injection current, thus demonstrating the importance of α as the system’s main nonlinearity. In particular, we demonstrate a drastic extension of the regime of coexistence between coherence collapsed dynamics and stable emission, and an increased stability of this stable emission state. We show that a theoretical analysis of the Lang-Kobayashi rate equation model provides a qualitative understanding of the physical mechanisms underlying the observed dynamical behavior and its dependence on α. Finally, being able to control the nonlinearity of the system, we open up new perspectives for the stabilization of semiconductor lasers subject to moderate to strong optical feedback.