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arXiv · 1210.5413

Failure of the α-factor in describing QD laser dynamical instabilities and chaos

Benjamin Lingnau·Kathy Lüdge·Weng W. Chow·Eckehard Schöll
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Abstract

We show that the long-established concept of a linewidth-enhancement factor αto describe carrier-induced refractive index changes in semiconductor lasers breaks down in quantum dot (QD) lasers when describing complex dynamic scenarios, found for example under high-excitation or optical injection. By comparing laser simulations using a constant α-factor with results from a more complex non-equilibrium model that separately treats gain and refractive index dynamics, we examine the conditions under which an approximation of the amplitude-phase coupling by an α-factor becomes invalid. The investigations show that while a quasi-equilibrium approach for conventional quantum well lasers is valid over a reasonable parameter range, allowing one to introduce an α-factor as a constant parameter, the concept is in general not applicable to predict QD laser dynamics due to the different timescales of the involved scattering processes.

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Benjamin Lingnau, Kathy Lüdge, Weng W. Chow, Eckehard Schöll. 2012-10-19. Failure of the α-factor in describing QD laser dynamical instabilities and chaos. https://doi.org/10.1103/physreve.86.065201

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