Optical probing of the Coulomb interactions of an electrically pumped polariton condensate

We report on optical probing of the Coulomb interactions in an electrically driven exciton-polariton laser. By positioning a weak non-resonant Gaussian continuous wave-beam with a diameter of 2 μm inside an electrical condensate excited in a 20 μm diameter micropillar, we study a repulsion effect which is characteristic of the part-excitonic nature of the microcavity system in strong coupling. It manifests itself in a modified real space distribution of the emission pattern. Furthermore, polariton repulsion results in a continuous blueshift of the emission with the increased power of the probe beam. A Gross-Pitaevskii equation approach based on modeling the electrical and optical potentials explains our experimental data.