Fibre optic connectors

- an overview or tutorial covering fibre optic connectors (fiber optic connectors) - the technology, how they work and their applications.

Optical Fibre Communications Includes:
Fibre communication basics Optical fibre Connectors Splicing Optical transmitter Optical receiver

There are many occasions when it is necessary to connect a fibre optic cable to another item. It may be that the fibre optic cable needs to be connected to another cable, or to an electronic interface device where the optical signal is converted to an electrical signal or to a light source. It is necessary that the fibre optic cable is correctly interfaced so that the minimum amount of light is lost. To achieve this it is necessary to use the correct form of fibre optic connector. In these cases fibre optic connectors are required.

While fibre optic connectors offer a very convenient method of connecting fibre optic cables, they should only be used where necessary. They introduce a loss at each connection. Typically the value is between 10 and 20 percent. Against this they make reconfiguring systems very much easier.

Connector basics

The fibre optic connector basically consists of a rigid cylindrical barrel surrounded by a sleeve. The barrel provides the mechanical means by which the connector is held in place wit the mating half. A variety of methods are used to ensure the connector is held in place, ranging from screw fit, to latch arrangements. The main requirement si that the end of the fibre optic cable is held accurately in place so that the maximum light transfer occurs.

As it is imperative that the optical fibre is held securely and accurately in place, connectors will normally be designed so that the fibre is glued in place, and in addition to this strain relief is also provided

Fibre ends may also be polished. For single mode fibre, the ends may be polished with a slight convex curvature so that the centres of the cables from the two connectors achieve physical contact. This approach reduces the back reflections, although the level of loss may be slightly higher.

Fibre optic connector types

Fibre optic connectors (fiber optic connectors) come in a variety of formats. These different fibre optic connectors may be used in slightly different applications or under different circumstances, as each type has its own capabilities.

When choosing a fibre optic connector, it is necessary to ensure that its properties meet the needs of the particular application in question. Some fibre optic connectors may be suitable for different optical fibres, and this needs to be taken into consideration.

There is a wide variety of different fiber optic connectors available. A selection of some is given below:

FC/PC This form of fibre optic connector is used for single-mode fiber optic cable. It provides very accurate positioning of the single-mode fiber optic cable with respect to transmitter (optical source) or the receiver (optical detector).
SC This form of connector is mainly used with single-mode fiber optic cables. The connector is simple low cost and reliable. The location and alignment is provided using a ceramic ferrule. It also has a locking tab to enable it to be mated and removed without fear of it accidentally falling loose.
Plastic fiber optic cable connectors As the name implies, these fibre optic cable connectors are only used with plastic fibre optic cabling.