Polariton-polariton scattering in semiconductor microcavities: Distinctive features and similarities to the three-dimensional case

Polariton-polariton scattering has been measured in a GaAs-based microcavity by a c.w. polarized photoluminescence technique using circularly and elliptically polarized resonant excitation into the lower polariton (LP) branch. The scattering has been found to be strongly enhanced when the singlet biexciton state is allowed as an intermediate one, i.e., under elliptically polarized excitation. An exponential growth of $k=0$ LP emission has been achieved at high excitation densities for the major spin population leading to the emission polarization degree higher than that of the excitation. The effect indicates the scattering stimulation appearing due to the bosonic nature of polaritons when the high filling of $k=0$ LP states is reached.