Fiber Connectors

A wide range of connector types is available.

The ST (Straight Tip) is the most popular connector because it is cheap and easy to install. Single mode versions differ from multimode in that they are made to finer tolerances and are more accurately aligned.

The SC connector was specified by the old EIA/TIA 568A specification, but its higher cost and difficulty of installation (until recently) limited its popularity. However, newer SCs cost less and are easier to install, so their use has been growing.

The duplex FDDI, ESCON and SC connectors are used for patch cords to equipment and can be mated to ST or SC connectors at wall outlets. Single mode networks use FC or SC connectors.

EIA/TIA 568 B allows any fibre optic connector that has is compatible with the FOCIS (Fiber Optic Connector Intermateability Standard). This allows the use of several new "Small Form Factor" (SFF) connectors, including AT&T LC, the MT-RJ, the Panduit "Opti-Jack," 3M's Volition, and the E2000/LX-5.

ST Connector

ST is the most common multimode fibre connector type, but can also be used for single mode. It consists of a bayonet mount and a cylindrical ferrule made from ceramic, metal or plastic. Typical insertion loss is around 0.25dB, but it is wise to allow for a loss of 0.5dB per connector. ST connectors are rated for 500 mating cycles.

FC/PC single mode connectors

FC/PC single mode connectors, screw on fitting and a keyway that must be aligned before tightening. Often replaced by SCs and LCs. Typical insertion loss is around 0.25dB, but it is wise to allow for a loss of 0.5dB per connector.

SC Connector

SC, a snap-in connector that is widely used in single mode systems, but can also be used for multimode. It's a snap-in connector that latches with a simple push-pull motion. Also available in a duplex configuration with two connectors side by side. Typical insertion loss is around 0.25dB, but it is wise to allow for a loss of 0.5dB per connector.

Small Form Factor (SFF) connectors

Where space is at a premium smaller connectors may be used.

LC single mode connector

LC single mode connector using a 1.25 mm ferrule, half the size of the ST, but can also be used for multimode. Typical insertion loss is around 0.25dB, but it is wise to allow for a loss of 0.5dB per connector. LC connectors are rated for 500 mating cycles.

MT-RJ is a duplex multimode connector

MT-RJ is a duplex multimode connector with both fibres in a single ferrule. Available in male and female versions. Typical insertion loss is around 0.25dB for multimode fibre and 0.35dB for single mode fibre, but it is wise to allow for a loss of 0.5dB per connector. MT-RJ connectors are rated for 1000 mating cycles.

Opti-Jack

Opti-Jack consists of two ST-type ferrules side by side in a package the size of a RJ-45. Male and female versions are available.

E2000/LX-5

E2000/LX-5 similar to LC but with a shutter to protect the fibre.

Connector Summary

ST/SC/FC/FDDI/ESCON connectors have a ferrule size of 2.5 mm. They can be matched using mating adapters.

For testing purposes you may find it useful to have a set of hybrid reference cables with connectors to suit your light sources, or a set of adapters for all these connectors.