Features of press-induced birefringence of light for Si and Ge crystals in the absorption frequency region

Peculiarities of the polarization change of transmitted and reflected light, incident normally to surface of a crystal, are experimentally and theoretically investigated. Such changes in polarization are caused due to anisotropy dielectric constant of crystal which can be either internal property of crystal or arises, for example, due to one- dimensional elastic deformation of a cubic crystal. At the significant absorption coefficient or great thickness L of a crystal the effect of polarization change is observed only for reflected light. Since in strong absorption case the 'active depth' of crystal can be compared with the length of probe wave, for registration of birefringence a special high- sensitivity-polarization-optical technique (HSPO) was worked out. The results obtained for Si and Ge crystals are discussed and qualitative comparison with the theoretical calculations are made.