Use of the longitudinal Pockels effect for measuring electroconductivity and photoconductivity of high-resistivity impure silenite crystals

Using the electro-optic longitudinal effect we have measured the electro- a nd photo-conductivity in photorefractive sillenite crystals with high resis tivity. We have studied doped samples with aluminum, chromium, vanadium, co balt, iron, and neodimium impurities distributed in the bulk or in a thin r egion near the surface. The data of the electro-optical measurements has be en completed with the spectra of optical absorption in the investigated sam ples.