Abstract

It is often anticipated that the linear optical properties of GaAs as a cubic material are isotropic. More careful consideration, however shows that spatial dispersion terms in the optical response lead to a small linear birefringence in this crystal. The crystal anisotropy becomes more pronounced in the nonlinear optical response where the symmetry of the nonlinear susceptibility tensors differs vastly from being isotropic. Local and non-local nonlinear anisotropy, for example, leads to the dependence of the efficiency of the two-photon absorption process on the crystal orientation and to a variety of nonlinear polarization-affecting phenomena for propagating light. Here we report the first observation of a new fine, but quite pronounced pump-probe polarization sensitive transient effect in reflected light which results directly from the anisotropy of the zinc-blende structure. It has the potential to become a new method for the investigation of cubic crystal anisotropy and nonlocality and is especially suitable for non-transparent materials such as narrow-gap semiconductors and superconductors where the application of transmission methods is not possible.

© 1994 Optical Society of America