AbstractFerroelectric (FE) thin films have been widely studied, especially for their electrical and ferroelectric properties, such as nonvolatile FE memory and ultrahigh density DRAMs. FE films also give rise to a variety of interesting and unique optical applications, such as electro-optic switches, passive and active waveguides, second harmonic generation, optical data storage, optical diodes and photovoltaic devices. Their dielectric properties have been extensively optimized but the optical and electro-optical aspects have not been satisfactorily explored. This paper will review the latest advances in the optical and electro-optical properties of FE films, highlighted by data obtained from our laboratories. Optical (refractive index and waveguiding loss) and electro-optical (linear (r33) and quadratic (R33) electro-optic coefficients) properties will be presented. Optimization of these properties by precise tailoring of chemistry, processing conditions and microstructure is discussed. Low optical loss, i.e., < 2dB/cm and an exceptionally high r33value of 315pm/V from PLZT films were obtained.