Thin film ferroelectrics are being developed for integrated optics applications. Their major advantage lies in their large electro-optic coefficients. Furthermore, they are nearly transparent from the mid-infrared to the visible spectral region. With the development of epitaxial deposition techniques for ferroelectrics, waveguide structures with low optical loss have been demonstrated. Through the use of epitaxial thin films deposited on low-index substrates, high-bandwidth electro-optic modulators have also been attained.