Crystal orientation dependence of the electro-optic effect in epitaxial lanthanum-modified lead zirconate titanate films

Lanthanum-modified lead zirconate titanate epitaxial films with (100), (101), and (111) orientations were grown on (100), (101), and (111) niobium lending conductivity strontium titanate using chemical solution deposition, respectively. We investigated the changes in the refractive index induced by the electric field in these films using the prism coupling method. Birefringence was observed in the (101)- and (111)-oriented epitaxial films induced by the electric field. However, no birefringence was observed in the (100) epitaxial film. This crystal orientation dependence of the electrooptic effect can be explained by the rotation of the refractive indicatrix that accompanies the switching of the polar clusters.