Controllable structuring of exciton-polariton condensates in cylindrical pillar microcavities

摘要

We observe condensation of exciton polaritons in quantum states composed ofconcentric rings when exciting cylindrical pillar GaAs/AlGaAs microcavitiesnon-resonantly by a focused laser beam normally incident at the center of thepillar. The number of rings depends on the pumping intensity and the pillarsize, and may achieve 5 in the pillar of 40 mkm diameter. Breaking the axialsymmetry when moving the excitation spot away from the pillar center leads totransformation of the rings into a number of bright lobes corresponding toquantum states with nonzero angular momenta. The number of lobes, their shapeand location are dependent on the spot position. We describe theout-of-equilibrium condensation of polaritons in the states with differentprincipal quantum numbers and angular momenta with a formalism based onBoltzmann-Gross-Pitaevskii equations accounting for repulsion of polaritonsfrom the exciton reservoir formed at the excitation spot and their spatialconfinement by the pillar boundary.