A
Adapter
A mechanical media termination device designed to align and join fiber optic connectors. Often referred to as a coupling, bulkhead, or interconnect sleeve.
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 ex-pressing 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); single-mode wavelengths are 1310 and 1550 nm. Note: When specifying attenuation, it is important to note whether the value is average or nominal.
B
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 multi-mode 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.
Cable
An assembly of optical fibers and other material providing mechanical and
environmental protection.
Cable Assembly
Optical fiber cable that has connectors installed on one or both ends. General
use of these cable assemblies includes the interconnection of optical fiber
cable systems and opto-electronic equipment. If connectors are attached
to only one end of a cable, it is known as a pigtail. If connectors are
attached to both ends, it is known as a jumper or patch cord.
Cable Bend Radius
Cable bend radius during installation infers that the cable is experiencing
a tensile load. Free bend infers a smaller allowable bend radius since it
is at a condition of no load.
Central Member
The center component of a cable. It serves as an antibuckling element to
resist temperature-induced stresses. Sometimes serves as a strength element.
The central member material is either steel, fiberglass, or glass-reinforced
plastic.
Centralized Cabling
A cabling topology used with centralized electronics connecting the optical
horizontal cabling with intra-building backbone cabling passively in the
telecommunications closet.
Cladding
The material surrounding the core of an optical wave-guide. The cladding
must have a lower index of refraction to keep the light in the core.
Coating
A material put on a fiber during the drawing process to protect it from
the environment and handling.
Composite Cable
A cable containing both fiber and copper media per article 770 of the National
Electrical Code (NEC).
Conduit
Pipe or tubing through which cables can be pulled or housed.
Connecting Hardware
A device used to terminate an optical fiber cable with connectors and adapters
that provides an administration point for cross-connecting between cabling
segments or interconnecting to electronic equipment.
Connector
A mechanical device used to align and join two fibers together to provide
a means for attaching to and decoupling from a transmitter, receiver, or
another fiber (patch panel). Commonly used connectors include the 568SC
(Duplex SC), ST compatible, FDDI, ESCON, SMA 905/906, Biconic, FC, or D4.
Connector Panel
A panel designed for use with patch panels; it contains either 6, 8, or
12 adapters pre-installed for use when field-connectorizing fibers.
Connector Panel Module
A module designed for use with patch panels; it contains either 6 or 12
connectorized fibers that are spliced to backbone cable fibers.
Core
The central region of an optical fiber through which light is transmitted.
Coupling
See Adapter.
Decibel (dB)
Unit for measuring the relative strength of light signals. Normally expressed
in dB, it is equal to one-tenth the common logarithm of the ratio of the
two levels. Expressed in dBm when a power level is compared to a milliwatt.
Dielectric
Non-metallic and, therefore, non-conductive. Glass fibers are considered
dielectric. A dielectric cable contains no metallic components.
Digital
A data format that uses two physical levels to transmit information corresponding
to 0s and 1s. A discrete or discontinuous signal.
Dispersion
The cause of bandwidth limitations in a fiber. Dispersion causes a broadening
of input pulses along the length of the fiber. Three major types are: (1)
modal dispersion caused by differential optical path lengths in a multimode
fiber; (2) chromatic dispersion caused by a differential delay of various
wavelengths of light in a waveguide material; and (3) waveguide dispersion
caused by light traveling in both the core and cladding materials in single-mode
fibers.
Entrance Facility
An entrance to a building for both public and private network service cables
including the entrance point at the building wall and continuing to the
entrance room or space.
Equipment Room
A centralized space for telecommunications equipment that serves the occupants
of a building. An equipment room is considered distinct from a telecommunications
closet because of the nature or complexity of the equipment.
FOTP
Fiber Optic Test Procedures. Defined in TIA/EIA Publication Series 455.
Fan-Out
Siecor multifiber cable constructed in the tight-buffered design. Designed
for ease of connectorization and rugged applications for intra- or interbuilding
requirements.
Ferrule
A mechanical fixture, generally a rigid tube, used to protect and align
a fiber in a connector. Generally associated with fiber optic connectors.
Fiber
Thin filament of glass. An optical waveguide consisting of a core and a
cladding that is capable of carrying information in the form of light.
Fiber Bend Radius
Radius a fiber can bend before the risk of breakage or increase in attenuation.
Fiber Distributed Data Interface (FDDI)
A standard for a 100 Mbit/s fiber optic local area network.
Fiber Optics
Light transmission through optical fibers for communication or signaling.
Fresnel Reflection Losses
Reflection losses that are incurred at the input and output of optical fibers
due to the differences in refraction index between the core glass and immersion
medium.
Fusing
The actual operation of joining fibers together by fusion or by melting.
Fusion Splice
A permanent joint produced by the application of localized heat sufficient
to fuse or melt the ends of the optical fiber, forming a continuous single
fiber.
Gigahertz (GHz)
A unit of frequency that is equal to one billion cycles per second, 109
Hertz.
Graded-Index
Fiber design in which the refractive index of the core is lower toward the
outside of the fiber core and increases toward the center of the core; thus,
it bends the rays inward and allows them to travel faster in the lower index
of refraction region. This type of fiber provides higher bandwidth capabilities
for multimode fiber transmission.
Horizontal Cabling
That portion of the telecommunications cabling that provides connectivity
between the horizontal cross-connect and the work-area telecommunications
outlet.The horizontal cabling consists of transmission media, the outlet,
the terminations of the horizontal cables, and horizontal cross-connect.
Horizontal Cross-Connect (HC)
A cross-connect of horizontal cabling to other cabling, e.g., horizontal,
backbone, equipment.
Hybrid Cable
A fiber optic cable containing two or more different types of fiber, such
as 62.5 µm multimode and single-mode.
IEEE
Institute of Electrical and Electronics Engineers.
Index-Matching Fluid
A fluid with an index of refraction close to that of glass that reduces
reflections caused by refractive-index differences.
Index of Refraction
The ratio of light velocity in a vacuum to its velocity in a given transmission
medium.
Interbuilding Backbone
The portion of the backbone cabling between buildings. See Backbone Cabling.
The portion of the backbone cabling within a building. See Backbone Cabling.
Jumper
Optical fiber cable that has connectors installed on both ends. See Cable
Assembly.
kpsi
A unit of force per area expressed in thousands of pounds per square inch.
Usually used as the speci-fication for fiber proof test, e.g., 100 kpsi.
See Aramid Yarn.
One thousand meters, or approximately 3,281 feet. The kilometer is a standard
unit of length measure-ment in fiber optics. Conversion is 1 ft. = 0.3048
m.
LAN
See Local Area Network.
Light Amplification by Stimulated Emission of Radia-tion. An electro-optic
device that produces coherent light with a narrow range of wavelengths,
typically centered around 780 nm, 1310 nm, or 1550 nm. Lasers with wavelengths
centered around 780 nm are commonly referred to as CD Lasers.
Light Emitting Diode (LED)
A semiconductor device used to transmit light into a fiber in response to
an electrical signal. It typically has a broad spectral width.
A telecommunications circuit between any two tele-communications devices,
not including the equipment connector.
A geographically limited communications network intended for the local transport
of voice, data, and video. Often referred to as a customer premises network.
Type of cable design whereby coated fibers are encased in buffer tubes offering
excellent fiber protection and segregation.
MDPE
Abbreviation used to denote medium density polyethylene. A type of plastic
material used to make cable jacketing.
The centralized portion of the backbone cabling used to mechanically terminate
and administer the backbone cabling, providing connectivity between equipment
rooms, entrance facilities, horizontal cross-connects, and intermediate
cross-connects.
Joining two fibers together by permanent or temporary mechanical means (vs.
fusion splicing or connectors) to enable a continuous signal. The CamSplice
is a good example of a mechanical splice.
A unit of frequency that is equal to one million cycles per second.
One millionth of a meter; 10-6 meter. Typically used to express the geometric
dimension of fibers, e.g., 62.5 µm.
Siecor loose tube cable in which the buffer tube contains two or more fibers,
typically 6 or 12 fibers.
A term used to describe an independent light path through a fiber, as in
multimode or single-mode.
The diameter of the one mode of light propagating in a single-mode fiber.
The mode field diameter replaces core diameter as the practical parameter
in single-mode fiber.
Coding of information onto the carrier frequency. This includes amplitude,
frequency, or phase modulation techniques.
An optical fiber cable that contains two or more fibers.
An optical waveguide in which light travels in multiple modes. Typical core/cladding
size (measured in micrometers) is 62.5/125.
Combining two or more signals into a single bit stream that can be individually
recovered.
A telecommunications outlet used to serve more than one work area, typically
in open-systems furniture applications.
National Electrical Code (NEC)
Defines building flammability requirements for indoor cables. Note: Local
codes take precedence but may refer to or require compliance to the NEC.
A unit of measurement equal to one billionth of a meter; 10-9 meters. Typically
used to express the wavelength of light, e.g., 1300 nm.
The number that expresses the light gathering ability of a fiber. Related
to acceptance angle.
Optical Fiber
See Fiber.
An instrument that measures transmission characteristics by sending a series
of short pulses of light down a fiber and providing a graphic representation
of the backscattered light.
PE
Abbreviation used to denote polyethylene. A type of plastic material used
for outside plant cable jackets.
Abbreviation used to denote polyvinyl-chloride. A type of plastic material
used for cable jacketing. Typically used in flame-retardant cables.
Abbreviation used to denote polyvinyl-difluoride. A type of material used
for cable jacketing. Often used in plenum-rated cables.
Optical fiber cable that has a connector installed on one end. See Cable
Assembly.
A semiconductor device used to convert optical signals to electrical signals
in a receiver.
An air-handling space such as that found above drop-ceiling tiles or in
raised floors. Also, a fire-code rating for indoor cable.
A connection established between two specific loca-tions as between two
buildings.
Fusing with a low current to clean the fiber end. Precedes fusion splicing.
Receiver
An electronic package that converts optical signals to electrical signals.
Reflectance is the ratio of power reflected to the incident power at a connector
junction or other compo-nent or device, usually measured in decibels or
dB. Reflectance is stated as a negative value, e.g., -30 dB. A connector
that has a better reflectance performance would be a -40 dB connector or
a value less than -30 dB. The terms return loss, back reflection, and reflectivity
are also used synonymously in the industry to describe device reflections,
but stated as positive values.
A device used to regenerate an optical signal to allow an increase in the
system length.
See Reflectance.
Pathways for indoor cables that pass between floors. It is normally a vertical
shaft or space. Also a fire-code rating for indoor cable.
Scattering
A property of glass that causes light to deflect from the fiber and contributes
to optical attenuation.
An optical waveguide (or fiber) in which the signal travels in one mode.
The fiber has a small core diameter, typically 9 µm.
A container used to organize and protect splice trays. Typically used in
outside plant environments.
A container used to secure, organize, and protect spliced fibers.
The permanent joining of bare fiber ends to another fiber. See Fusion Splice
and Mechanical Splicing.
Telecommunications Closet (TC)
An enclosed space for housing telecommunications equipment, cable terminations,
and cross-connects. The closet is the recognized cross-connect between the
backbone and horizontal cabling.
Type of cable construction whereby each glass fiber is tightly buffered
by a protective thermoplastic coating to a diameter of 900 micrometers.
Increased buffering provides ease of handling and connectorization.
An electronic package used to convert an electrical information-carrying
signal to a corresponding optical signal for transmission by fiber. The
transmitter is usually a Light Emitting Diode (LED) or Laser Diode.
UL
Underwriters Laboratories, Inc.
Wavelength
The distance between two successive points of an electromagnetic waveform,
usually measured in nanometers (nm).
A connecting device located in a work area at which the horizontal cabling
terminates and provides connectivity for work-area patch cords.
Zero-Dispersion Wavelength
Wavelength at which the chromatic dispersion of an optical fiber is zero.
Occurs when waveguide dispersion cancels out material dispersion.
Intermediate Cross-Connect (IC)
A secondary cross-connect in the backbone cabling used to mechanically terminate
and administer backbone cabling between the main cross-connect and horizontal
cross-connect.
Intrabuilding Backbone
Kevlar
Kilometer (km)
LASER Diode
Link
Local Area Network (LAN)
Loose Tube Cable
Main Cross-Connect (MC)
Mechanical Splicing
Megahertz (MHz)
Micrometer (µm)
Mini Bundle Cable
Mode
Mode Field Diameter
Modulation
Multifiber Cable
Multimode Fiber
Multiplex
Multi-User Outlet
Nanometer (nm)
Numerical Aperture (NA)
Optical Time Domain Reflectometer (OTDR)
PVC
PVDF
Pigtail
PIN Diode
Plenum
Point-to-Point
Prefusing
RH
Relative humidity.
Reflectance
Repeater
Return Loss
Riser
Single-Mode Fiber
Splice Closure
Splice Tray
Splicing
Tight-Buffered Cable
Transmitter
Work-Area Telecommunications Outlet
