Electro-optic effects refer to the change in the optical properties of a material when an electric field is applied. This phenomenon can alter the refractive index of the material, affecting how light passes through it. Common materials exhibiting these effects include LiNbO3 (lithium niobate) and KTP (potassium titanyl phosphate), which are often used in various optical devices. These effects are crucial in applications such as modulators, which control light signals in telecommunications, and switches in optical circuits. By manipulating light with electric fields, electro-optic devices enable faster and more efficient data transmission in modern technology.