Femtosecond studies of the excitonic optical Stark effect in an anisotropically strained multiple quantum well

Femtosecond pump and probe measurements with linearly polarized light pulses have been employed in the study of the excitonic optical Stark effect in a GaAs/AlGaAs MQW under in-plane anisotropic strain. A significant dependence of the photoinduced blue shift and bleaching of the lowest heavy-hole-like exciton resonance on the orientation of the pump and probe polarization vectors with respect to the axis of maximum compressive strain has been observed. Theoretical calculations performed using the generalized anisotropic multiband semiconductor Bloch equations provide a qualitative explanation of the experimental results.