Abstract: An optical deflector device has a substrate having an electro-optical effect and capable of guiding rays of light therethrough, a buffer layer formed on one of opposite major surfaces of the substrate, and first and second deflection electrodes formed on respective first and second portions of the buffer layer to produce an electric field within the substrate, so that the light rays passing through the substrate are deflected in response to a change in the distribution of a refractive index of the substrate according to a controlled deflection voltage applied to the deflection electrodes. The deflector device includes an isolator for isolating the first and second portions of the buffer layer from each other. The isolator may be a groove or grooves formed through the thickness of the buffer layer to separate the first and second portions.