The 4 Ports 1550nm Polarization Maintaining Optical Circulator is a high-performance, non-reciprocal passive optical device that routes light sequentially from Port 1 → Port 2 → Port 3 → Port 4, while precisely maintaining the polarization state of the transmitted signal. Operating at the 1550 nm wavelength, this device offers low insertion loss, high isolation, high return loss, and an excellent polarization extinction ratio (PER), making it ideal for advanced polarization-sensitive optical systems.