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. This means that if light enters port 1 it is emitted from port 2, but if some of the emitted light is reflected back to the circulator, it does not come out of port 1 but. In the rapidly evolving field of fiber optics, the 3-port circulator has emerged as a critical component for efficient optical signal routing. Our Single Mode (SM) and Polarization-Maintaining (PM) Circulators are ideal for advanced communication systems and fiber sensor.