Exciton Polaritons in two-dimensional Photonic Crystals

We report on experimental evidence of strong coupling between excitons confined in a quantum well and the photonic modes of a two-dimensional dielectric lattice is reported. Both resonant scattering and photoluminescence spectra at low temperature show the anticrossing of the polariton branches, fingerprint of strong coupling regime. The experiments show that the polariton dispersion can be tailored by properly varying the photonic crystal lattice parameter, which enlarges the possibility of engineering polariton dispersion. The data are successfully interpreted in terms of a quantum theory of exciton photon coupling in such nanostructures.