MATERIALS CONSTANTS OF KNBO3 RELEVANT FOR ELECTROOPTICS AND ACOUSTOOPTICS

The elastic, piezoelectric, dielectric, elasto-optic, and electro-opti c tensors have been determined by numerically evaluating the measureme nts published until now and using the additional measurements presente d in this work. The dependence of the speed of two elastic waves on th e applied electric field is measured yielding one electroelastic const ant g13133 = (95 +/- 10)NV-1 m-1. The complete set of parameters consi sting of the low-frequency clamped dielectric constants epsilon(ij)S, refractive indices, elastic stiffness constants at constant electric f ield C(ijkl)E piezoelectric coefficients e(ijk), elasto-optic tensor a t constant electric field p(ijkl)E, and clamped electro-optic coeffici ents r(ijk)S is used to calculate effective electro-optic coefficients and effective dielectric constants that have to be used in photorefra ctive experiments where the elastic deformations associated with a per iodic space-charge field have to be considered.