The Electro-Optic Effect refers to the change in the optical properties of a material when an electric field is applied. This effect can alter the refractive index of the material, which affects how light passes through it. It is commonly observed in certain crystals, such as LiNbO3 and KTP, and is utilized in various optical devices. This phenomenon is essential in technologies like modulators and switches, where controlling light signals is crucial. By applying an electric field, these devices can manipulate light for applications in telecommunications and information processing, enhancing the performance of optical systems.