Strain-induced anticrossing of bright exciton levels in single self-assembled GaAs/AlxGa1-xAs and InxGa1-xAs/GaAs quantum dots

We study the effect of elastic anisotropic biaxial strain, induced by a piezoelectric actuator, on the light emitted by neutral excitons confined in different kinds of epitaxial quantum dots. We find that the light polarization rotates by up to similar to 80 degrees and the fine structure splitting (FSS) varies nonmonotonically by several tens of mu eV as the strain is varied. These findings provide the experimental proof of a recently predicted strain-induced anticrossing of the bright states of neutral excitons in quantum dots. Calculations on model dots qualitatively reproduce the observations and suggest that the minimum reachable FSS critically depends on the orientation of the strain axis relative to the dot elongation.