A type of fiber-optic cabling that can carry only one signal at a time. Single-mode fiber-optic cabling uses light generated by a laser-emitting diode to carry signals.
Laser light is extremely stable and uniform and can be accurately focused, making it perfect for long-distance transmission. Single-mode fiber has extremely low signal attenuation and is typically used for long cable runs because it can generally carry signals up to 50 times farther than multimode fiber, which can carry many different signals simultaneously.
Single-mode fiber typically has a core that is only 5 or 10 micrometers in diameter - much smaller than the core of multimode fiber, which needs room to carry many different light signals simultaneously.
Use single-mode fiber-optic cabling for long cable runs or where extra bandwidth is required. The bandwidth of single-mode fiber is typically double that of multimode fiber. Be aware, however, that installing single-mode fiber requires more care and expertise to avoid signal loss, especially if you terminate the cable with connectors. Single-mode fiber is also more expensive than multimode because multimode systems use transmitters that have cheaper light-emitting diodes, while single-mode systems use more expensive laser-emitting diodes in their transmitters. Also, when you use single-mode fiber-optic cabling, the ancillary devices such as line drivers cost more.