Role of symmetry reduction in the polarization dependence of the optical absorption in non-common-atom superlattices

Ab initio calculations of the dielectric tensor elements show that the mechanism underlying the experimentally observed giant polarization anisotropy of the optical absorption in non-common-atom superlattices is a "selection rule" by which the radiation polarization along the 110 or -110 directions chooses only one transition of the doublet degenerate in common-atom superlattices. The magnitude of the anisotropy depends only on the energy splitting between the two hole states. Our results suggest ways to enhance the anisotropy through manipulation of interface structure or chemistry or strain condition.