Abstract
Optical response nonlocality in cubic ZnSe in the proximity of an excitonic absorption resonance leads to a gigantic optical anisotropy (δn/n 0.1). The anisotropy cause a polarization azimuth rotation, in scale of several degrees, for the light reflected from the [110] crystal facet. The anisotropy is described by quadratic, in respect to the light wave vector terms in the dielectric tensor of the crystal. It results from the, spin-orbit interaction induced, electron-wave vector linear terms in the exciton dispersion, bound to non-centrosymmetricity of the crystalline structure.