Normally, optical cable comes in two types, namely, single mode fiber (SMF) and multimode fiber (MMF).
Single mode fiber has a very thin core about 5-10 microns in diameter while multimode fiber has a core diameter of about 10 times of a single mode fiber. Generally, single mode optical fibers used in telecommunications operate at 1310nm or 1550nm wavelength while multimode fiber at 850nm and 1300nm.
Compared with single mode fiber, multimode fiber has a limited transmission distance by model dispersion because it has a large core size and supports more than one light mode (from OM1 to OM5).
Single mode fiber is suitable for long distance applications such as 100km between buildings while multimode optical fiber is used in short distance transmission within buildings such as computer network linking.