LINEAR TERMS IN (Q)OVER-RIGHT-ARROW IN THE MACROSCOPIC OPTICAL-PROPERTIES DF ZINCBLENDE TYPE MATERIALS - THEORY AND EXPERIMENT

Situations under which off-diagonal symmetric or antisymmetric terms in the dielectric tenser epsilon(ij)(omega, q ($) over bar) of zincblende-type materials, proportional to the wavevector of the light q ($) over bar; may exist are reviewed and clarified. Off-diagonal linear terms in q ($) over bar have been associated with macroscopic effects on the polarization of the light of two different kinds: optical activity (antisymmetric) and gyrotropic birefringence (symmetric). Contrary to recent reports concerning GaAs, we show that gyrotropic birefringence caused by the symmetric off-diagonal linear terms in the dielectric tensor does not exist in bulk crystals under equilibrium conditions. Any such reported effects should be attributed to residual internal stress or surface effects.