Optical crystals are materials that have unique properties to manipulate light. They can bend, reflect, or transmit light in specific ways, making them essential in various applications like lasers, lenses, and optical devices. Common examples of optical crystals include quartz, calcite, and sapphire. These crystals are often used in telecommunications, imaging systems, and scientific instruments due to their ability to control light effectively. Their structure allows for precise interactions with light waves, enabling technologies such as fiber optics and photonic devices to function efficiently.