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 be originated by 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.
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