Polarization Dependent Excitonic Optical Nonlinearities in GaAs/AlGaAs Multiple Quantum Wells under Anisotropic In-Plane Strain

The photoinduced bleaching and blueshift of the lowest heavy-hole-like exciton in an anisotropically strained multiple quantum well exhibits a large enhancement for femtosecond light pulses polarized parallel to the axis of maximum compressive strain relative to those measured using orthogonally polarized light. These results imply that the strain-induced anisotropy in $k$ space leads to exciton-exciton interactions which possess a strong dependence on the orientation with respect to the strain axis, relative orientation, and spatial extent of the photogenerated excitonic dipoles.