Exciton-polaritons condensation at non-zero momentum in pump-induced potential in ZnO microwire

We studied the condensation of exciton-polaritons in pump-induced potential by angle-resolved photoluminescence (PL) measurements at room temperature. The experimental dispersion spectrum shows that under the excitation of a small spot, polaritons in ZnO whispering gallery microcavity condense at a certain state where momentum is non-zero. This is different from the conventional Bose-Einstein condensation (BEC) in which case the polaritons condense at ground state with a zero momentum. The theoretical simulation of condensation shape given by Gross-Pitaevskii equation (GPE) is in good agreement with our experimental observations.