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We present a theoretical analysis of the emission of localized excitons in GaAs‐AlGaAs quantum wells, which shows a strong nonlinear behavior with increasing excitation. Considering the influence of dynamical screening both on the one‐particle properties of carriers and on the whole spectrum of electron‐hole pair states, we are able to explain the nonlinearity as a transition of the emission from excitonic to electron‐hole pair states in the continuum (electron‐hole plasma). Moreover, our theoretical approach based on the quasi‐particle approximation for the carriers states and quantum kinetic effects in the screening describes the observed changes of the shift of the exciton energy from higher to lower energies at a temperature of T = 10 K (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

We study the fluorescence light emitted from GaAs excitons in semiconductor quantum wells. The excitons are modeled as interacting bosons. By combining quantum optical methods for the excitonic emission spectrum with many particle descriptions of the transmission through the medium, we can evaluate the spectra outside the well. Comparing with experimental spectra, we get a very good agreement. The method helps explaining the main features of the observed spectra. It is demonstrated that the observed spectra show clear evidence of superfluorescent emission.Comment: revised version; accepted for publication in PR

Micropillar cavities of different diameters have been excited optically. The photoluminescence spectra of the top face emission have been measured while studying their intensity profile with high spatial resolution through the use of microscope objectives within the cryostat.The “donut”‐shape of the cavity mode with the second highest intensity is shown for the 2.3 µm pillar. A transfer matrix method has been applied to estimate the spatial and spectral profile of the individual cavity modes for comparison with the experimental results. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)