Inhomogeneous radiative decay of polariton modes in a two-dimensional excitonic system

The problem of radiative decay of coherent polariton modes in a two-dimensional excitonic system with strong exciton-photon coupling is analyzed here. We show, theoretically, that inhomogeneous plane electromagnetic waves are spontaneously emitted from such a system. The dispersion branches of radiative exciton-polaritons penetrate into the slow-wave region of the ω−k∥ dispersion plane where they exhibit appreciable renormalization of their frequency. We conclude that slow radiative polaritons can be observed in time-resolved photoluminescence experiments on PbI-based self-organized quantum-well structures at grazing angles of emission.