Multistability of cavity exciton-polaritons affected by the thermally   generated exciton reservoir
  Until now, the generation of an excitonic reservoir in a cavity polariton system under quasi-resonant pumping has always been neglected. We show that in microcavities having a small Rabi splitting (typically GaAs cavities with a single quantum well), this reservoir can be efficiently populated by polariton-phonon scattering. We consider the influence of the exciton reservoir on the energy shifts of the resonantly pumped polariton modes. We show that the presence of this reservoir effectively reduces the spin anisotropy of the polariton-polariton interaction, in agreement with recent experimental measurements, where the multistability of cavity polaritons has been analyzed 
D. V. Vishnevsky, D. D. Solnyshkov, N. A. Gippius, G. Malpuech
cond-mat.mes-hall physics.optics