Mainz 1997 – wissenschaftliches Programm

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Q: Quantenoptik

Q 34: Halbleiterlaser

Q 34.8: Vortrag

Mittwoch, 5. März 1997, 17:45–18:00, N 6

Quantum Noise and Polarization Fluctuations in Vertical Cavity Surface Emitting Lasers — •Holger F. Hofmann and Ortwin Hess — Theoretische Quantenelektronik, Institut f"ur Technische Physik, DLR, Pfaffenwaldring 38-40, D-70569 Stuttgart

The theoretical investigation of polarization stability in vertical cavity surface emitting lasers (VCSELs) has shown that both frequency and gain-loss anisotropies may selectively stabilize a linear direction of polarization. However, the experimental evidence available does not allow a distinction between the processes. In order to learn more about the mechanism of polarization stability in VCSELs, we therefore determine the polarization noise properties predicted by a rate equation model with both frequency and gain-loss anisotropies in the presence of quantum noise. Our results show, that the frequency and gain-loss anisotropies can be determined separately from time resolved polarization noise measurements. In addition, such measurements provide data on the spin relaxation rate in the quantum well structure during cw operation. Indeed, all parameters used in the rate equation model may be obtained from precise measurements of the intensity and polarization fluctuations in the emitted laser light. We therefore propose time resolved measurements of the noise properties of laser light emitted from VCSELs as an experimental tool for the characterization of VCSELs, especially with respect to the effects of anisotropies and of quantum well confinement on the laser process.