Polariton states bound to defects in GaAs/AlAs planar microcavities

Abstract

We report on polariton states bound to defects in planar GaAs/AlAs microcavities grown by molecular beam epitaxy. The defect types relevant for the spatial polariton dynamics in these structures are cross-hatch misfit dislocations, and point-like defects extended over several micrometers. We attribute the latter defects to Ga droplets emitted occasionally by the Ga cell during the growth. These defects, also known as oval defects, result in a dome-like local modulation of surface, which is translated into the cavity structure and leads to a lateral modulation of the cavity polariton energy of up to 15 meV. The resulting spatially localized potential landscape for the in-plane polariton motion creates a series of bound states. These states were characterized by spectrally resolved transmission imaging in real and reciprocal space, and reveal the spatial potential created by the defects. Interestingly, the defect states exhibit long lifetimes in the 10 ps range, which we attribute to a spatially smooth confinement potential.

Temperature Dependence of Highly Excited Exciton Polaritons in Semiconductor Microcavities

“…33. Although we have not obtained direct evidence of the e-h pair correlation in the high-excitation regime, recent observations of a ghost polariton branch 34,35 using an intense resonant excitation laser indicate the possibility of e-h pairs and polaritons even in the high-density regime.…”

Suppression of cross-hatched polariton disorder in GaAs/AlAs microcavities by strain compensation

“…A detailed description of the setup can be found in Ref. 17. The measured cavity mode wavelengths are shown in Table I and are red detuned by 50-80 meV from the bulk GaAs exciton 18 of the cavity layer at 1.508 eV.…”

Spatial multistability induced by cross interactions of confined polariton modes

“…By laterally confining light either by engineering the microcavity [11][12][13][14], or by the use of oval defects [15], it is possible to create a series of spatially distinct, confined polariton modes when these new cavity modes are strongly coupled to an exciton in a quantum well (QW). Therefore, taking advantage of the nonlinearity in the optical response of the polariton modes resulting from the exciton-exciton interactions, we can coherently excite this system to obtain the spatial multistability simply by changing the excitation power.…”