Fibre types explained: OM3, OM4, OS2, multimode and single-mode.

Fibre carries more, further, than copper. Choosing the type is mostly about distance.

Multimode (OM3, OM4, OM5)

Wider core, cheaper optics, suited to runs inside buildings and short campus links. OM3 and OM4 support 10 gigabit over a few hundred metres and higher speeds over shorter distances. OM4 reaches further than OM3.

Single-mode (OS2)

Thin core for long distances, from hundreds of metres to many kilometres. Optics cost more, but the cable is future-proof, since the same fibre handles higher speeds with better transceivers.

Which to pick

• Within a building: multimode is common; single-mode is increasingly chosen to avoid rework.
• Between buildings on a campus: single-mode is usually the sound choice.
• Long runs and carrier links: single-mode.

Connectors and polish

LC is the common small connector. SC remains in older plant. Use matching polish types, since mixing them damages signal quality and connectors.

Transceivers must match

A multimode transceiver does not work reliably on single-mode, and the reverse. Match wavelength, distance and speed.

Practice

Clean connectors before mating, keep bend radius, label both ends and test with a power meter or OTDR. Document the result.