Fibre optics or optical fibres are long, thin strands of very pure glass about the diameter of a human hair.
Arranged in bundles called optical cables, fibre optics is used to transmit light signals over long distances. The bundles are protected by the cable's outer covering called a jacket.
How optical fibre cables work
Quite similar to using mirrors on walls to angle a light beam down a hallway with multiple bends, the light in a fibre optic cable travels through the core (hallway) by constantly bouncing from the cladding (mirror-lined walls) using a principle called total internal reflection.
Since the cladding does not absorb any light from the core, the light wave can travel great distances.
Multi-Mode Fibre Optic Cables 50/125 and 62.5/125 Micron
Multi-mode is a type of fibre optic cable thick enough for light to follow several paths through its core.
Multi-mode fibre is suitable for use in short lengths such as those used in Local Area Networks (LANs) and Storage Area Networks (SANs).
Multi-mode fibre optic cables are available in two standard widths of 62.5 micron and 50 micron.
The 62.5 micron (OM1) multi-mode fibre can support Gigabit Ethernet over distances as long as 275 metres while the 50 micron (OM3) multi-mode fibre can increase that range to 550 metres.
Single Mode Fibre Optic Cables 9/125 Micron
Single mode fibre optic cables are highly suitable for long-haul use.
The cable has a small 9-micron core that forces the light to follow a more linear single path down the cable, as opposed to the multipath reflections of multi-mode cables.
Using lasers as the usual light source, these cables are highly expensive and very difficult to manufacture.
Single mode fibre offers extremely high bandwidths and distance ratings.