Page 145 - Optical Communications Essentials

Connectors and Splices

Connectors and Splices 135

This specifies beige for multimode fibers and blue for single-mode fibers. Duplex
SC connectors are used widely on two-fiber patch cords and have been designed
with a keying mechanism to maintain fiber optic cabling polarity. The word polar-
ity means that the ends of a cable are matched properly for transmit and receive
functions. Basically the duplex configuration combines two standard SC connec-
tors in a common duplex plastic housing. This housing is keyed to maintain fiber
polarity and provides smooth insertion and removal of the connector pairs.

FC connector. FC optical fiber connectors were designed specifically for telecom-
munication applications. This connector uses a threaded coupling mechanism,
as illustrated in Fig. 8.14. Connector mating is done by means of bulkhead
feedthrough adapters. These adapters combine a metal housing and either a
precision ceramic or a rugged metal alignment sleeve. The connectors come in
a preassembled, one-piece body design and have prepolished ferrules. This
enables quick and economical terminations in both factory and field settings. This
also ensures a uniform end-face geometry, thereby yielding consistent optical
performance. Nominal insertion losses are less than 0.15dB with single-mode
fibers and less than 0.34dB for multimode fibers.
An FC connector can be mated with an SC connector by one of two methods.
In the first method, to directly connect them, a hybrid FC/SC connector adapter
will accept an FC connector on one side and an SC connector on the other side.
Both connectors should be flat-polished (not angle-polished) for this method to
work. The second method uses a hybrid jumper cable and two connector
adapters. A hybrid jumper is a cable with two different connectors on each end.
These connectors should match the two connectors that are to be mated. This
will allow regular connector adapters to be used in the patch panels to connect

Figure 8.14. Example of an FC connector. (Photo courtesy of
Fitel Interconnectivity Corporation; www.fitelconn.com.)

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