  Polariton spin carries the combination of the exciton and the photon spin,
which is manifested in the circularly polarized emission degree in a III-V
quantum wells microcavity system. Relaxation process of such spin system is a
complex subject since it involve upper or lower polariton branch, resonant or
non resonant polariton excitation process and if the particles are in strong or
weak coupling regime. We present here experimental polariton spin Faraday
rotation time measurement in GaAs single quantum well microcavity, using time
resolved polariton photoluminescence by resonant excitation process in a
pump-probe system.
