We investigate the polarization dynamics of the secondary emission from a disordered quantum well after resonant excitation. Using the speckle analysis technique we determine the coherence degree of the emission, and find that the polarization-relaxed emission has a coherence degree comparable to the one of the emission co-polarized to the excitation. This is explained by the finestructure splitting between the two optically active states of anisotropically localized excitons. The eigenstates are linearly polarized with distributed orientations. The time evolution of the involved eigenstate doublets leads to a polarization dynamics and to a speckle intensity correlation between the orthogonal light polarizations. A model considering localized exciton states in an anisotropically Gaussian-correlated potential landscape gives a consistent description of the experimental observations. For a 4 nm GaAs quantum well, an anisotropy along the  direction with correlation lengths of 28 nm along and 17 nm perpendicular is deduced, leading to an average fine-structure splitting of 29 mu eV.
|Journal||IPPS physica status solidi (b)|
|Publication status||Published - 2000|
|Event||6th International Workshop on Nonlinear Optics and Excitation Kinetics in Semiconductors - Marburg, Germany|
Duration: 10 Apr 2000 → 13 Apr 2000
Conference number: 6
|Workshop||6th International Workshop on Nonlinear Optics and Excitation Kinetics in Semiconductors|
|Period||10/04/2000 → 13/04/2000|