Coexistence of Low Frequency Fluctuations and stable emission on a single high-gain mode in semiconductor lasers with external optical feedback

We present a systematic investigation of the dynamical behavior of semiconductor lasers subject to external optical feedback in dependence on the injection current and the optical feedback strength. We identify the regimes of Low Frequency Fluctuations (LFF), fully developed coherence collapse, and, for the first time, a large regime of coexistence of LFF and stable emission on single high-gain external-cavity mode extending over more than one order of magnitude of optical feedback strengths. Thus, we provide experimental evidence for one major prediction of the theoretical model based on the LangKobayashi equations which proposes a deterministic mechanism underlying to the LFF