Mesocavities support simultaneous interactions of exciton to few cavity modes. Such situation occurs when strength of exciton-photon interaction (Rabi splitting) and energy interval between cavity modes are comparable. Recently, non-monotonic dependence of the occupancy of polariton states on the pumping intensity has been observed.

Figure. Dependence of the population of polariton modes on pumping. For polariton modes with energies below the exciton energy, anomalous hysteresis loops are observed with a nonmonotonic dependence of the population on pumping.

A. V. Belonovskii, V. V. Nikolaev, E. I. Girshova
JETP Letters 117, issue 2 (2023)