Polarization dynamics of optically pumped VCSELs

We consider the polarization dynamics of optically pumped vertical-cavity surface-emitting lasers (VCSELs) with a pump light of arbitrary polarization ellipticity. We also consider the effect of an applied transverse magnetic field on the polarization properties of the output light. We first test our theoretical description by analyzing the polarization state of the photoluminescence light emitted by an optically pumped quantum well, and discuss a variety of phenomena known to originate from spin carrier dynamics in these materials. We discuss how these phenomena are modified when a VCSEL is operated above threshold, and we show that our model gives a good description of Larmor oscillations observed in VCSELs excited with short optical pulses. For VCSELs under continuous optical pump, we find a number of accessible experimental situations in which self-sustained polarization oscillations in the emitted light are possible. We identify and analyze three different mechanisms for these oscillations to occur. When no magnetic field is applied, we find polarization oscillations governed by birefringence and undamped polarization oscillations at the relaxation oscillation frequency. With an applied magnetic field, we find self-sustained oscillations governed by the Larmor frequency. In addition, our study of optically pumped VCSELs makes apparent the effects of spin carrier dynamics in the polarization properties of the emitted light.