An optical fibre (or optical fibre) is a flexible, transparent fibre made by drawing glass (silica) or plastic.
Optical fibres typically include a transparent core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fibre to act as a waveguide. Fibres that support many propagation paths or transverse modes are called multi-mode fibres (MMF), while those that support a single mode are called single-mode fibres (SMF). Multi-mode fibres generally have a wider core diameter and are used for short-distance communication links and for applications where high power must be transmitted.
An important aspect of a fibre optic communication is that the losses brought about by joining two different cables are kept to a minimum. For applications that demand a permanent connection, a mechanical splice which holds the ends of the fibres together mechanically could be used or a fusion splice that uses heat to fuse the ends of the fibres together could be used. Temporary or semi-permanent connections are made by means of specialized optical fibre connectors.