Exciton-lattice polaritons in multiple-quantum-well-based photonic crystals

摘要

Coherent interaction of an ensemble of dipole active atoms orexcitons with a vacuum electromagnetic field has been studiedextensively since its initial conception by Dicke in 19541-6.However, when the emitters are not only periodically arrangedas in refs 2 to 4, but are also placed in a periodically modulateddielectric environment, the interaction between them is carriedby the electromagnetic Bloch waves of the photonic crystal7,8.Here we report the first observation of this effect using a peri-odic arrangement of GaAs/AlGaAs quantum wells. The for-mation of coherently coupled photonic-crystal excitonic-latticepolaritons manifests in our experiments through enhancedreflectivity and reconstruction of the photonic bandgap in thevicinity of the excitons. Experimental evidence of hybrid lighthole-heavy hole excitonic-lattice polaritons is also presented.Coherent coupling between excitons and Bloch waves is estab-lished through comparisons of the experimental results withtheory. Finally, we demonstrate the tuning of these polaritonstates by an electric field.