Coherence of excitonic secondary emission quantified by time resolved speckle analysis

Summary form only given. Near band-edge optical properties in undoped semiconductor nanostructures at low temperatures are often dominated by excitonic processes. Present interest is focusing on the coherence properties of light emission after short-pulse excitation. Emission in a non-specular direction involves scattering processes, and the temporal emission dynamics allows to look into the corresponding microscopic mechanisms such as interface roughness, phonon emission, or exciton-exciton interaction. If static disorder dominates, the scattering is elastic (Rayleigh scattering) and preserves the coherence. The other extreme is incoherent luminescence which has lost all phase memory. A clear distinction between the two cases is not possible in experiments where the emission is collected within a wide detection angle. The key point for the novel method presented here is that the existence of speckles in a one-pulse experiment can be taken as an indicator for coherence in the emitted radiation.