Regensburg 2010 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 30: Posters II

DY 30.29: Poster

Donnerstag, 25. März 2010, 16:00–18:00, Poster C

Optical Feedback Tolerance of Quantum-Dot Compared to Quantum-Well Lasers — •Christian Otto, Kathy Lüdge, and Eckehard Schöll — Institut f. Theo. Physik, Sekr. EW 7-1, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

In experiments quantum-dot (QD) lasers display lower feedback sensitivity than quantum-well (QW) lasers. This advantageous dynamical behaviour is ascribed to their smaller phase-amplitude coupling that is expressed in small linewidth enhancement factors α. In this work we investigate the complex dynamics of both laser types subjected to external optical feedback from a distant mirror. To model the QW laser we use a conventional Lang-Kobayashi model with one equation for the complex field and one equation for the carrier inversion. The QD laser is modeled with a modified Lang-Kobayashi equation for the electric field combined with microscopically based rate equations for the carriers in the quantum dots and the surrounding wetting layer.

By varying the feedback strength we obtain complex bifurcation scenarios. For large α>3 we find bifurcation cascades leading to chaotic regions alternating with short regions of stable continuous wave (cw) operation. However, for low α < 1 the model exhibits a reduced feedback sensitivity and performs stable cw operation over a wide range of increasing feedback strength.

By comparison of QW and QD diagrams we find that QD lasers are indeed more tolerant to optical feedback. Furthermore for the same value of α the routes to chaos are different for QD and QW lasers.