An optical coupler is a device that connects two optical fibers, allowing light to pass from one fiber to another. It is essential in telecommunications and data transmission, as it helps to combine or split light signals without significant loss of quality. Optical couplers can be used in various applications, including fiber optic networks and laser systems. These devices come in different types, such as fiber couplers and waveguide couplers, each designed for specific functions. By efficiently managing light signals, optical couplers play a crucial role in enhancing the performance of optical systems and ensuring reliable communication.