Polycrystalline ferroelectric optical devices

An optical device comprises a body of ferroelectric material exhibiting an effective electro-optic coefficient (reff) and an optical loss (alpha), with the body being adapted for the propagation of optical radiation at a wavelength lambdo through it, and means for applying an electric field to the body in order to alter the refractive index therein, characterized in that the body is polycrystalline and has an average grain size such that reff is relatively high and alpha is relatively low, both at lambdo. In a preferred embodiment the body has an average grain size that is less than about lambdo/10, preferably in the range of approximately 8-20 nm, which is especially well suited for devices operating at near infrared wavelengths in the range of about 1000-1600 nm. Illustratively, the ferroelectric body is a perovskite material such as barium titanate or lithium niobate.