Evaluation of electro-optic, elasto-optic, piezoelectric, and elastic coefficients of Ba0.77Ca0.23TiO3 through orientation dependent photorefractive beam coupling

We present a demonstration of the influence of the indirect electro-optic effect on the photorefractive performance of Ba0.77Ca0.23TiO3 (BCT). The comparison of the orientation dependence of the two-beam coupling energy transfer gain with theoretical model allows us to obtain information on the electro-optic coefficients, but also an evaluation of the unknown elasto-optic, piezoelectric, and elastic stiffness coefficients of BCT. We found r(13)(T)=33 pm V-1 and r(33)(T)=170 pm V-1. These values are in good agreement with other published values. For the interesting coefficient r(42)(T), we find a higher value r(42)(T)=465 pm V-1 than the one previously published. From this study we also determine that as in the case of BaTiO3, the optimal orientation is given by a 45degrees-cut BCT. (C) 2002 American Institute of Physics.