Elektrotransmission und Pockelseffekt an Zinkoxid

Abstract

We report measurements of the electrotransmission on zincoxide. The main interest is on a structure due to the Pockelseffect. The later causes a rotation of the ellipsoid of wave normals near the isotropic point (Δn=0 for λ_i=396.3 nm) and produces, combined with the dichroitic absorption, a pronounced modulation of the transmitted light intensity, which is not connected to a critical point in the band-structure. The observed structure can be explained and calculated in detail by means of the phenomenological theory of Pockels taking into account the symmetry of the total system crystal and electric field. Two values of the Pockels-constants at low frequencies are given.