Optical properties of epitaxial plzt thin films

In the epitaxial (Pb1−x, Lax)(Zr1−y, Tiy)1−x/4O3 [PLZT] films, the composition dependence of the refractive index and electric-optic (EO) coefficient near the morphotropic phase boundary (MPB) composition was investigated. A (100/001)-oriented PLZT 10/65/35 epitaxial film is found to have isotropic optical properties. Highly (100/001)-oriented epitaxial PLZT films with compositions near the MPB on Nb–SrTiO3 substrates were fabricated using a sol–gel process. The value of birefringence from 4 × 10−3 to 5 × 10−4 in PLZT epitaxial film was smaller than that of lithium niobate single crystal. The refractive index decreases with increasing lanthanum content. The difference in the refractive index obtained depended upon the lanthanum content up to 2%. This value is adequate for fabrication of waveguide structures. The EO coefficient of PLZT 9/65/35 thin films was 45 pm/V, which is larger than that of lithium niobate single crystal. A very small polarization dependence of the EO coefficient was also observed.