Dresden 2009 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 5: Nanophotonics - Theory of Nanophotonic Devices I

DS 5.3: Vortrag

Montag, 23. März 2009, 12:15–12:30, GER 38

Sensitivity of Quantum-Dot Lasers to Optical Feedback — •Christian Otto, Kathy Lüdge, Ermin Malić, and Eckehard Schöll — Institut für Theoretische Physik, Sekr. EW 7-1, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin

Low sensitivity of a laser to back reflected light, a property needed for industrial device application, is predicted for semiconductor quantum dot (QD) lasers. In this work we investigate the complex dynamics of QD lasers subjected to weak external optical feedback from a distant mirror. The system 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 surrounding wetting layer.

By varying the feedback strength we obtain complex bifurcation scenarios. For large linewidth enhancement factors (α>3) we find a bifurcation cascade leading to chaotic regions alternating with short regions of stable cw operation. This resembles the behaviour found in quantum well lasers. However, for low α-factors around α=1, typical for QD devices, the laser exhibits a reduced feedback sensitivity and performs stable cw operation over a wide range of increasing feedback strength.