Electro-optic materials are substances that change their optical properties in response to an electric field. These materials can alter their refractive index, which affects how light passes through them. This property is crucial for applications in devices like modulators and switches, where controlling light signals is essential. Common examples of electro-optic materials include lithium niobate and potassium titanyl phosphate (KTP). These materials are widely used in telecommunications and laser technology, enabling faster data transmission and improved signal processing. Their unique characteristics make them vital for modern optical systems and photonic devices.