Optical Anisotropy In Gaas/Alxga1-Xas Multiple-Quantum Wells Under Thermally-Induced Uniaxial Strain

The effect of thermally induced in-plane uniaxial strain on the optical properties of a GaAs/AlxGa1-xAs multiple quantum well (MQW) has been studied in detail. The strain was produced by bonding the MQW thin films to LiTaO3, a transparent substrate which possesses a direction-dependent thermal expansion coefficient. At temperatures different from the bonding temperature we have observed an anisotropy in the optical properties of the MQW due to the strain-induced lowering of its in-plane fourfold rotation symmetry. The anisotropic absorption and birefringence for light incident normal to such a MQW structure have been determined and compared to a theory involving the mixing of the valence subbands.