A fiber optic patch cord consists of two wires

Fiber optic patch cords can have either one or two fibers, with duplex cords containing two fibers for bidirectional communication.Basic StructureA fiber optic patch cord, also called a fiber jumper, is a cable with connectors on both ends used to connect fiber optic devices such as switches, transceivers, and patch panels . Inside the patch cord, the optical fibers carry light signals, and the cable may include protective elements like Kevlar yarn for strength and a jacket for environmental protection .Single vs Duplex FibersSimplex patch cords contain a single fiber and transmit data in one direction only. One end acts as the transmitter, and the other as the receiver .Duplex patch cords contain two fibers, allowing bidirectional communication. One fiber transmits data while the other receives, making them suitable for applications requiring simultaneous two-way data transfer . This explains why many fiber optic patch cords appear to have "two wires"—they are duplex cords designed for bidirectional transmission.Fiber Types and ApplicationsSingle-mode fibers (yellow jacket) are used for long-distance communication with low attenuation .Multimode fibers (OM1/OM2 orange, OM3 aqua, OM4 violet, OM5 lime green) are used for shorter distances and high-bandwidth applications . Duplex cords are common in data centers, telecom networks, and enterprise environments where bidirectional communication is essential .ConnectorsPatch cords use various connectors such as LC, SC, FC, ST, MPO, and MT-RJ. Duplex cords often use LC or SC connectors in a duplex configuration, with two fibers aligned side by side for easy insertion into equipment .SummaryWhile a fiber optic patch cord can be simplex (one fiber) or duplex (two fibers), the "two wires" you observe are typically the two fibers in a duplex patch cord, enabling bidirectional data transmission. This design is standard in modern networking and telecommunications setups .