  We demonstrate experimentally the condensation of exciton-polaritons through
optical trapping. The non-resonant pump profile is shaped into a ring and
projected to a high quality factor microcavity where it forms a 2D repulsive
optical potential originating from the interactions of polaritons with the
excitonic reservoir. Increasing the population of particles in the trap
eventually leads to the emergence of a confined polariton condensate that is
spatially decoupled from the decoherence inducing reservoir, before any build
up of coherence on the excitation region. In a reference experiment, where the
trapping mechanism is switched off by changing the excitation intensity
profile, polariton condensation takes place for excitation densities more than
two times higher and the resulting condensate is subject to a much stronger
dephasing and depletion processes.
