An optical circulator is a passive, non-reciprocal, multi-port device typically designed with three or four terminals. It ensures that light entering any port is transferred sequentially to the next adjacent port in a specific, predetermined direction. Optical circulators are a key component in modern optical networks, crucial for directing light beams in telecommunications and. Fiber optic circulators act as signal routers, transmitting light from an input fiber to an output fiber, but directing light that returns along that output fiber to a third port. They perform a similar function as an isolator, protecting the input fiber from return power, but also allowing the.