153Optical fiberCAUTION:Use the same types of transceiver modules, pigtail cords, patch cords, and fiber cables. If you usesingle-mode optical fibers, the transceiver modules, pigtail cords, patch cords, and fiber cables must besingle-mode.OverviewOptical fiberOptical fibers are widely used in fiber-optic communications, which are advantageous for long-distancecommunications.Optical fibers can be classified into the following types:• Single mode fiber: It has a core size of 10 μm, and has a lower modal dispersion. It carries only asingle ray of light. It is mostly used for communication over longer distances.• Multi-mode fiber: It has a core size of 50 μm or 62.5 μm or higher, and has a higher modaldispersion than single-mode optical fiber. It is mostly used for communication over shorterdistances.Table 81 Allowed maximum tensile force and crush loadPeriod of force Tensile load (N) Crush load (N/mm)Short period 150 500Long term 80 100Optical fiber cableAn optical fiber cable is a cable containing one or more optical fibers. The optical fiber elements aretypically individually coated with plastic layers and contained in a protective tube. Optical fiber cablesfall into single-mode and multi-mode.Patch cordA fiber that has connectors at both ends is called a patch cord. A patch cord connects one optical deviceto another for signal routing. Patch cords fall into single-mode and multi-mode patch cords.• Single-mode patch cord: The jacket is yellow. It permits transmission over longer distances.• Multi-mode patch cord: The jacket is orange. It permits transmission over shorter distances.Patch cords are classified into SC, LC, and FC patch cords based on interface type. The length of a patchcord can be 0.5 m (1.64 ft), 1 m (3.28 ft), 2 m (6.56 ft), 3 m (9.84 ft), 5 m (16.40 ft), and 10 m (32.81ft).Pigtail cordA pigtail cord is an optical fiber that has an optical connector on one end and a length of exposed fiberon the other. The end of the pigtail is fusion spliced to a fiber, connecting the fiber cable and transceiver.Pigtail cords fall into single-mode (yellow) and multi-mode (orange), and can also be classified into SC,LC, and FC pigtail cords based on interface type.
