Fiber Optic Connectors Guide

Optical connectors are available in a wide variety of styles and types. Choosing which one to use is usually decided by the type of connector already installed in the equipment to be connected. Nevertheless, adapters are generally available in either sleeve connectors or patch cords to allow coupling of different types of connectors.

All of the common types of connectors are fairly simple to install. With just weeks worth of installer practice one can expect losses no higherthan 2% to 5%, depending on the cleanliness of the area in which the connections are made.

Before fiber connectors are installed, a breakout kit may need to be used. This procedure will be required on 250-, 500-, and 900-micron tight-buffer cables. The bare fibers are inserted into those buffer tubes to provide handling protection and strength when mounted onto connectors.

Some popular connectors for various applications are listed below:

MT-RJ Used for networking applications. It's actually a little smaller than a standard phone jack, and just as easy to connect and disconnect. It's half the size of the SC connector it was designed to replace.
FDDI Used for networking applications. Duplex connector with fixed shroud, keyed.
ESCON Used for Data and Voice network applications (Duplex)
ST One of the most commonly used fiber optic connectors in networking applications. Cylindrical with twist lock coupling, 2.5mm keyed ferrule. For both short distances applications and long line systems.
SC Used frequently for newer network applications. Square, keyed connector with push-pull mating, 2.5mm ferrule and molded housing for protection.
SMA The SMA fiber connector is decreasing in popularity.
FC/PC Widely used Fiber optic Connector
D4 Decreasing in use\
Biconic Decreasing in use.
LC
MU Connector
Toslink Connector

CONNECTOR INSTALLATION GUIDE

Installing a fiber connector onto a pigtail or un-buffered fiber can be done in several ways. The three most common are epoxy glue with oven-cure, then polish; Hot Melt pre-glue, then polish; and cleave and crimp, no polish.

The epoxy-glue method is the oldest and is still widely used today. This process involves filling the connector with a mixed two-party epoxy, then inserting the prepared and cleaned fiber into the connector. After curing the epoxy in an oven for the specified period of time (usually 5 to 20 minutes), the fiber is scribed and cleaved nearly flush with the end of the connector. Finally, it's polished with a succession of finer and finer lapping papers (typically ranging from 3-micron grit down to 0.3-micron grit).

With Hot Melt method (a trademark of 3M Co.), the connector comes preloaded with glue and must be placed into an oven to soften the glue. Clean, prepared fiber is then inserted into the connector, then left to cool. After cooling, the fiber is scribed and polished in the same process as used in the epoxy method.

Cleave and crimp connectors do not require a polish procedure since these connectors already have a polished ferrule tip. Thus, installation simply involves inserting a properly cleaved fiber to butt against the connector's internal fiber "stub." The fiber connector is then crimped to hold the fiber in place.