Figure 6-9.—Basic ferrule connector design.
Butt-jointed connectors and expanded-beam
connectors are the two basic types of fiber-optic
connectors. Fiber-optic butt-jointed connectors align
and bring the prepared ends of two fibers into close
contact. The end faces of some butt-jointed connectors
touch, but others do not. depending upon the connector
design. Types of butt-jointed connectors include
cylindrical ferrule and biconical connectors. Figure 6-9
shows a basic ferrule design. Fiber-optic expanded-
beam connectors use two lenses to first expand and
then refocus the light from the transmitting fiber into the
receiving fiber. Single fiber butt-jointed and expanded-
beam connectors normally consist of two plugs and an
adapter (coupling device) (fig. 6-10).
Expanded-beam connector shown in figure 6-11
uses two lenses to expand and then refocus the light
from the transmitting fiber into the receiving fiber.
Expanded-beam connectors are normally plug-adapter-
plug type connections Fiber separation and lateral
misalignment are less critical in expanded-beam
coupling than in butt-jointing. The same amount of
fiber separation and lateral misalignment in expanded-
beam coupling produces a lower coupling loss than in
butt-jointing; however, angular misalignment is more
critical. The same amount of angular misalignment in
expanded-beam coupling produces a higher loss than in
butt-jointing. Also, expanded-beam connectors are
much harder to produce. Resent applications for
expanded-beam connectors include multifiber
connections, edge connections for printed circuit
boards, and other applications.
FIBER-OPTIC COUPLERS
Some fiber-optic data links require more than
simple point-to-point connections. These data links
may be of a much more complex design that requires
multiport or other types of connections. In many cases,
these types of systems require fiber-optic components
that can redistribute (combine or split) optical signals
throughout the system.
One type of fiber-optic component that allows for
the redistribution of optical signals is a fiber-optic
coupler. A fiber-optic coupler is a device that can
distribute the optical signal (power) from one fiber
among two or more fibers. Also, a fiber-optic coupler
Figure 6-10.—Plug-adapter-plug configuration.
6-10
