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Absorption
The loss of light energy in an optical fiber resulting from impurities in
the glass.

Acceptance Cone
A cone angled area that light must enter in order to "bounce" down
the fiber, or travel between the core and the cladding.

Acrylate
Acrylic resin.

Adapter
A mechanical media termination device designed to align and join
fiber optic connectors. Often referred to as a coupling, bulkhead, or
interconnect sleeve.

All-dielectric
Non-conducting; made entirely of dielectric (insulating) materials,
without any metal conductors.

Analog
A format that uses continuous physical variables such as voltage
amplitude or frequency variations to transmit information.

Aramid Yarn
Strength elements that provide tensile strength and provides support
and additional protection of the fiber bundles. Kevlar® is a
particular brand of aramid yarn.

Armor
Additional protective element beneath outer jacket to provide
protection against severe outdoor environments. Usually made of
plastic-coated steel, it may be corrugated for flexibility.

Attenuation
The decrease in magnitude of power of a signal in transmission
between points. A term used for expressing the total loss of an
optical system, normally measured in decibels (dB) at a specific
wavelength.

Attenuation Coefficient
The rate of optical power loss with respect to distance along the
fiber, usually measured in decibels per kilometer (dB/km) at a
specific wavelength. The lower the number, the better the fiber's
attenuation. Typical multimode wavelengths are 850 and 1300
nanometers (nm); singlemode wavelengths are 1310 and 1550 nm.
Note: When specifying attenuation, it is important to note whether
the value is average or nominal.
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Backbone Cabling
The portion of premises telecommunications cabling that provides
connections between telecommunications closets, equipment
rooms, and entrance facilities. The backbone cabling consists of the
transmission media (optical fiber cable), main and intermediate
cross-connects, and terminations for the horizontal cross-connect,
equipment rooms, and entrance facilities. The backbone cabling can
further be classified as interbuilding backbone (cabling between
buildings), or intrabuilding backbone (cabling within a building).

Bandwidth
Measure of the information-carrying capacity of an optical fiber.
Note: This term is often used to specify the normalized modal
bandwidth (MHz·km) of a multimode fiber. See Dispersion for
single-mode fibers.

Bandwidth-Distance Product
The information-carrying capacity of a transmission medium is
normally referred to in units of MHz·km. This is called the
bandwidth-distance product or, more commonly, bandwidth. The
amount of information that can be transmitted over any medium
changes according to distance. The relationship is not linear,
however. A 500 MHz·km fiber does not translate to 250 MHz for
a 2 kilometer length or 1000 MHz for a 0.5 kilometer length. It is
important, therefore, when comparing media, to ensure that the
same units of distance are being used.

Broadband
Typically referring to copper, it denotes transmission facilities
capable of handling a wide range of frequencies simultaneously, thus
permitting multiple channels in data systems, rather than direct
modulation.

Buffering
(1) A protective material extruded directly on the fiber coating to
protect it from the environment (tight-buffered); (2) extruding a tube
around the coated fiber to allow isolation of the fiber from stresses
in the cable (buffer tubes).

Buffer Tubes
Extruded cylindrical tubes covering optical fiber(s) used for
protection and isolation. See Loose Tube.

Bundle
Many individual fibers contained within a single jacket or buffer
tube. Also, a group of buffered fibers distinguished in some fashion
from another group in the same cable core.