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Q: Quantenoptik

Q 25: Poster: Halbleiterlaser

Q 25.1: Poster

Dienstag, 25. März 2003, 16:30–18:30, Lichthof

Polarization switching to the mode with lower linear net gain in vertical-cavity surface-emitting lasers — •Markus Sondermann, Michael Weinkath, and Thorsten Ackemann — Institut für Angewandte Physik, Westfälische Wilhelms-Universität Münster, Corrensstr. 2-4, 48149 Münster, Germany

The polarization state of the light emitted by vertical-cavity surface-emitting lasers can exhibit a variety of dynamical phenomena. The most prominent one is the switching from one linearly polarized fundamental transverse mode to the orthogonal one at increasing current (e.g. [1]). Intrinsic anisotropies result in different emission wavelengths and in different linear (i.e. unsaturated) net gains of these modes. At threshold, typically the mode with the higher linear net gain is lasing [1]. In this contribution, we report on the experimental observation of switching to the mode with lower linear net gain for the case of switching from the shorter to the longer wavelength mode. This switching is identified by a decrease of output power and relaxation oscillation frequency at the switching point. The experimental observations are compared to a dynamical model [2] that incorporates non-linear relaxation processes among inversion populations with opposite spin and a complex frequency dependent susceptibility of the semiconductor gain material. The complementary switching from the mode with longer wavelength to the mode with shorter wavelength is also investigated. The experimental and theoretical results agree on a qualitative level.

[1] M.P. van Exter, et al., Phys. Rev. A 58, 4191 (1998).

[2] S. Balle, et al., Opt. Lett. 24, 1121 (1999).