Fiber optic circulators rely on non‑reciprocal optical principles, typically using a combination of polarisation optics, Faraday rotators, and beam splitters. These components manipulate the polarisation state of light so that it follows a fixed directional path regardless of the. An Optical Circulator is a non-reciprocal passive device used in fiber optic communication systems to control the direction of light propagation. Typically, it has three or four ports: Port 1: Entry point for the incoming light signal. You can think of it as a traffic controller for light, ensuring signals flow in one direction without interference.