Optical imaging of exciton-polaritons probability density in cylindrical traps

We use optical spectroscopy for imaging the probability density of microcavity exciton-polaritons confinedin a cylindrical trap. Composite half-matter half-light quasi-particles, the exciton-polaritons exhibit anextremely light effective mass, allowing to confine them inside traps of the size of several micrometers insize. Confined polaritons are therefore unique systems allowing a direct optical access to confined quasi-particles wavefunctions, in opposition to standard quantum confinement means in semiconductors, such asquantum dots.The traps for polaritons are made of circular mesas, providing a local increased thickness of the micro-cavity length, therefore a lateral confinement for the photonic part of the polariton [1, 2]. The excitonicmatter wave being strongly coupled to the confined photon modes, discrete confined levels are observed forboth upper and lower polaritons.Energies and spatial distributions of the confined polariton states are succesfully compared to the solu-tions of the time-independant Schr¨odinger equation for a particle confined in a cylindrical potential well,using the effective mass of the microcavity polariton.