  Semiconductor microcavities offer unique means of controlling light-matter
interactions, which have led to the development of a wide range of applications
in optical communications and inspired proposals for quantum information
processing and computational schemes. Studies of spin dynamics in microcavities
- a new and promising research field - have revealed novel effects such as
polarization beats, stimulated spin scattering, and giant Faraday rotation.
Here, we study the electron spin dynamics in optically-pumped GaAs microdisk
lasers with quantum wells (QWs) and interface-fluctuation quantum dots (QDs) in
the active region. In particular, we address the question of how the electron
spin dynamics are modified by the stimulated emission in the disks, and observe
an enhancement of the spin lifetime when the optical excitation is in resonance
with a high quality (Q ~ 5000) lasing mode. This resonant enhancement, contrary
to what is expected from the Purcell effect observed in the cavities, is then
manipulated by altering the cavity design and dimensions.
