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DY: Dynamik und Statistische Physik

DY 34: Nonlinear Dynamics, Synchronization and Chaos I

DY 34.7: Vortrag

Mittwoch, 29. März 2006, 16:00–16:15, H\"UL 186

Coherence resonances in semiconductor lasers — •Oleg V. Ushakov, H-J. Wünsche, F. Henneberger, I. A. Khovanov, L. Schimansky-Geier, and M.A. Zaks — Humboldt Universität zu Berlin, Inst. für Physik, Newtonstr. 15, 12489 Berlin, Germany

Semiconductor laser with ultrashort optical feedback are excellent candidates to study novel scenarios of self-organization in optical systems. We have investigated the influence of external Gaussian noise close to the onset of sub- and super-critical Hopf bifurcations. Noise-induced oscillations appear as a Lorentzian-shaped peak in the power spectrum. The coherence factor defined by the product of height and quality factor (width divided by frequency) exhibits non-monotonous behavior with a distinct maximum at a certain noise intensity for both types of Hopf bifurcations, demonstrating coherence resonance. However, the spectral width of the peak behaves qualitatively different. Whereas it increases monotonically for the supercritical bifurcation, a pronounced minimum is observed for the subcritical case. These experimental findings are examined in terms of general potential models for the noise driven motion close to bifurcations [V.S. Anishchenko, et al., Nonlinear Dynamics of Chaotic and Stochastic Systems (Springer, Berlin, Heidelberg 2002)]. We conclude that our observations reveal a generic mode for the occurrence of coherence resonance in non-linear systems.