Parametric amplification and polariton liquids in semiconductor microcavities

Abstract

Parametric amplification in semiconductor microcavities provides an example in which nonlinear optical interactions produced by the exchange interaction of excitons become so large that multiple scattering of polaritons becomes important. Here we review time-resolved observations of the polariton interactions in a number of different geometries including pumping at either the magic angle, or the bottom of the polariton trap. Situations in which the polariton dispersion is multiply occupied by large populations give rise to k-dependent energy shifts, modifying the dispersion dynamically, a situation we term the strongly interacting ‘polariton liquid’