Condensation of polaritons through optical confinement: Increased coherence and reduced threshold

We report on a fully optically confined exciton-polariton condensate, spatially separated from the pump induced excitonic reservoir and analyze its formation process. The optically trapped condensate exhibits higher coherence features and an order of magnitude lower excitation density threshold with respect to previous excitation schemes as a result of the reduction of dephasing and depletion mechanisms associated with the interaction with the reservoir.