Exciton-photon interaction in low-dimensional semiconductor microcavities

The structure of the photon states and dispersion of cavity polaritons in semiconductor microcavities with two-dimensional optical confinement (photon wires), fabricated from planar Bragg structures with a quantum well in the active layer, are investigated by measuring the angular dependence of the photoluminescence spectra. The size quantization of light due to the wavelength-commensurate lateral dimension of the cavity causes additional photon modes to appear. The dispersion of polaritons in photon wires is found to agree qualitatively with the prediction for wires having an ideal quantum well, for which the spectrum is formed by pairwise interaction between exciton and photon modes of like spatial symmetry. The weak influence of the exciton symmetry-breaking random potential in the quantum well indicates a mechanism of polariton production through light-induced collective exciton states. This phenomenon is possible because the light wavelength is large in comparison with the exciton radius and the dephasing time of the collective exciton state is long. Zh. éksp. Teor. Fiz. 114, 1329–1345 (October 1998)