Formation of a macroscopically occupied polariton state in a tunable open-access microcavity under resonant excitation

We experimentally demonstrate the formation of a macroscopically occupied state (condensation) of exciton-polaritons in a tunable 3D open-access microcavity system under resonant excitation. We observe a high conversion efficiency of polaritons from the pumped state to the ground mode, leading to the population of the condensate 1.5 times greater than that of the driven state for a total number of polaritons of ∼110. Comparative numerical simulations show that coherent polariton-polariton scattering mechanisms alone cannot explain the observed experimental results and that other relaxation channels play an important role.