  The formation and propagation of a polariton condensate under tightly focused
excitation is investigated in a ZnO microcavity both experimentally and
theoretically. 2D near-field and far-field images of the condensate are
measured under quasi-continuous non-resonant excitation. The corresponding
spatial profiles are compared to a model based on the Gross-Pitaevskii equation
under cylindrical geometry. This work allows to connect the experiments
performed with a small excitation laser spot and the previous kinetic models of
condensation in a 2D infinite microcavity, and to determine the relevant
parameters of both the interaction and the relaxation between the reservoir and
the condensate. Two main parameters are identified: the exciton-photon detuning
through the polariton effective mass and the temperature, which determines the
efficiency of the relaxation from the reservoir to the condensate.
