Discretized disorder in planar semiconductor microcavities: Mosaicity effect on resonant Rayleigh scattering and optical parametric oscillation

The features of resonant secondary emission by two-dimensional multiple semiconductor microcavities are experimentally investigated. The multiband photonic/polaritonic dispersion makes possible a normal laser incidence which represents an isotropic probe of the system defectivity. We show that the static disorder determines the final states of the resonant Rayleigh scattering in the high-symmetry axes of the GaAs matrix. Scanning transmission electron microscopy and x-ray-diffraction measurements reveal the origins of disorder: a small misfit dislocation density and step formation at the layer interfaces due to strain accumulation and relaxation. These mosaicity effects ruled by the symmetry of the underlying GaAs matrix are common features of thick and strained crystals and determine the scattering channels by selecting the crystallographic discretized directions. The structural characterization demonstrates that, while the presence of misfit dislocations plays a minor role, the principal source of disorder is due to the elastic relaxation of strain. Moreover, interband optical parametric oscillation of the intensity balanced signal and idler beams is seeded by the resonant Rayleigh scattering and takes place in the directions selected by the photonic disorder in the distributed Bragg reflector.