Bulk exciton polaritons in GaAs microcavities

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Abstract
The optical properties of excitons in thin layers are significantly different from those in bulk crystals. In particular, we study the case of a bulk material of thickness comparable with the wavelength of the excitonic transition confined on one or on both sides by appropriate Bragg reflectors. If the cavity resonance quasimode is carefully tuned on the excitonic transition, strong exciton-photon coupling takes place and produces a Rabi-like splitting as large as that observed in quantum-well-implanted microcavities and comparable optical absorption. In addition, the polaritonic spatial dispersion and the quantization of the exciton center-of-mass motion introduce remarkable fine structures which are absent in the quantum-well case. We demonstrate the above effects from a spectroscopic analysis of GaAs cavities and compare them with those displayed by quantum-well-implanted microcavities.