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Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - International Research Training Group 1740

S Ruschel and S Yanchuk (2017)

Chaotic bursting in semiconductor lasers

Chaos: An Interdisciplinary Journal of Nonlinear Science, 27(11):114313.

We investigate the dynamic mechanisms for low frequency fluctuations in semiconductor lasers subjected to delayed optical feedback, using the Lang–Kobayashi model. This system of delay differential equations displays pronounced envelope dynamics, ranging from erratic, so called low frequency fluctuations to regular pulse packages, if the time scales of fast oscillations and envelope dynamics are well separated. We investigate the parameter regions where low frequency fluctuations occur and compute their Lyapunov spectra. Using the geometric singular perturbation theory, we study this intermittent chaotic behavior and characterize these solutions as bursting slow-fast oscillations. The regime of low frequency fluctuations (LFFs) is one of the most intriguing dynamical phenomena observed in semiconductor lasers with delayed feedback. This regime is characterized by chaotic fluctuations of the optical amplitude, which are interrupted by irregular amplitude dropouts occurring on a much slower timescale than the amplitude oscillations. In the last decade, a series of theoretical studies have investigated this phenomenon and discovered several important aspects of LFFs. In particular, the time-delayed feedback and timescale separation between the photon and carrier dynamics appear to be important ingredients for the appearance of LFFs. Also, the stationary lasing modes, so called external cavity modes, are shown to be related to the creation of the LFF attractor. In this work, we describe LFFs as well as other more regular solutions, so-called regular pulse packages (RPPs), as bursting slow-fast oscillations. We show that they, being weakly chaotic, are precursors of strong chaos in the system. In addition, we thoroughly investigate the parameter regions, where LFFs and RPPs occur.