Fiber Optic Network Cables and Connectors

Fiber Optic Network Cables and Connectors

Fiber optics have slowly but steadily taking over from copper wire as a primary means for digital communications. The advantages of fiber optics make it possible to transmit data over longer distances, with lower attenuation, run multiple data lines side by side, without problems from crosstalk and allow data lines to cross power lines, without the risk of electrical noise.

While copper network cables are only able to go about 90 meters without amplification, while fiber optic cables can make runs of several kilometers without repeaters. For cases where networks need to make connection over longer distances, fiber optic cables are a clear winner.

Likewise, the fact that there are no electrical signals or copper wires to pick up spurious electrical noise signals make them an excellent option for use in electronically “noisy” environments, such as manufacturing operations. This advantage is so great, that most central computer systems for companies are fiber optic based, rather than copper based. It’s only at the workstation level that copper is still commonly used.

The reason that copper is common at the workstation level is that it is still considered less expensive than fiber optics. This perception is based mostly on the cost of converters, rather than the actual cost of the fiber optic line as compared to copper Cat-5 and Cat-6 lines.

Through the years, a wide variety of fiber optic cables have been developed. Of these, only a few are used for computer networks. The greatest number is used for cable television, the biggest consumer of fiber optic.
Those used for networking are:

fiber ST connector

ST Connector

The ST connector, developed by AT&T, was one of the first common fiber optic connectors used for networking. The name stands for the fact that the fiber optic end is straight cut and polished. The connector body is 2.5 mm, with a quarter-turn bayonet sleeve to lock it in place. These are being phased out and replaced by smaller connectors which can be packed denser.

fiber FC connector

FC Connector

The FC connector is a threaded body fiber optic connector, typically used in applications where high vibration is a problem. The threaded metal body resists loosening better than other connector types. These are becoming less common, as they are being replaced by SC and LC connectors.

fiber SC connector

SC Connector

The SC connector, developed by the Japanese telecommunications company NCC, incorporates an easier to use push on snap coupling connector body, with a similar single fiber transmission line. It was developed to be easier to work with than the ST connector and succeeded in fulfilling that goal.

fiber SC duplex connector

SC Duplex Connector

The SC Duplex connector is a common configuration of the SC connector, where two standard SC connectors are molded into the same housing. This allows bi-directional communication over a pair of fiber optic lines

fiber LC connector

LC Connector

The LC connector, designed by Lucent Technologies, was developed to provide a more compact connector which could be packed denser in backplanes and connector boards. The fiber optic ferrule is 1.25mm, half the size of the SC and ST connectors. Like the SC Duplex connector, these are often mounted for use in pairs. They are held in place by a locking tab.

fiber Fo7 connector

F07 Connector

The F07 connector was developed as a Japanese Industrial Standard for LAN and audio applications. It is compatible with ST connectors. These are not common outside of industrial uses.

fiber MTRJ connector

MTRJ Connector

The MTRJ connector, sometimes listed as MT-RJ was developed to surpass previous connectors in saving space. These are a duplex connector in a single housing, drastically reducing the footprint of the mating connector on the circuit board. The abbreviation stands for “mechanical transfer registered jack.” It borrows much of its design from the RJ style modular plug.

A variety of fiber optic cables are available on the market, using these connectors; singly, or in combinations. For combination cables, it is important to specify the connector types used at both ends. As the connector type has nothing to do with the data format, any combination of fiber optic connectors can be used, without having to reformat the data.

If unsure of the type of connector that a piece of computer equipment uses, be sure to check the owner’s manual, which will list the connector type.


Rich Murphy