INVESTIGATIONS OF GIANT FORBIDDEN OPTICAL ANISOTROPY IN GAINAS-INP QUANTUM-WELL STRUCTURES

We report the unexpected observation of a large polarization anisotrop y of the optical absorption for light propagating parallel to the grow th axis of InGaAs-InP multi-quantum well structures. This effect, whic h is forbidden in the classical envelope function theory, is associate d with the reduced overall symmetry of heterostructures where the host materials have no common atom: the breakdown of the fourfold rota-inv ersion symmetry for interface atoms leads to a non-local coupling of t he heavy- and light-hole states, responsible for the optical anisotrop y. The experimental results are compared with tight-binding calculatio ns of the optical properties.