Aa
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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 cable tensile strength, support and
additional protection of the fiber bundles. Kevlar® is a particular brand
of aramid yarn.
Armor
Additional protective element beneath the cable 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); single-mode 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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Bb
----------
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, such as with colored binder threads.
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Cc
----------
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 stranded loose-tube cable. It serves as an antibuckling element to
resist temperature-induced stresses. 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 intrabuilding backbone cabling passively in the
telecommunications closet.
Cladding
The material surrounding the core of an optical waveguide. The cladding
must have a lower index of refraction to keep the light in the core.
Coating
A material applied to a fiber during the draw 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
providing 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 insert designed for use with patch panel housings. Connector panels often contain either 6, 8, or
12 adapters pre-installed for use when field-connectorizing fibers.
Connector Panel Module
A connector panel module designed for use with patch panels. It contains either 6 or 12
connectorized fibers that are spliced to backbone cable fibers.
Consolidation
The second manufacturing step in the OVD process; manufacturing step which
removes water vapor from the preform, and sinters it into a solid, dense,
transparent glass blank.
Core
The central region of an optical fiber through which light is transmitted.
Coupling
See Adapter.
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Dd
----------
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.
Draw
The third and final step in the OVD process; draws the glass blank into
a continuous strand of glass fiber.
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Ee
----------
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.
Extrinsic
External; outside the fiber.
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Ff
----------
FOTP
Fiber Optic Test Procedures. Defined in TIA/EIA Publication Series 455.
Fan-Out
Corning Cable Systems tight-buffered breakout style multifiber cable 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.
Frequency
The number of pulses or cycles per second; measured in units of Hertz (Hz)
where 1 hertz equals 1 pulse/cycle per second.
Fusing
The actual operation of joining fibers together by fusion or by melting.
Fusion Splicing
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.
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Gg
----------
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.
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Hh
----------
Hertz (Hz)
The frequency in pulses/cycles per second where 1 hertz equals 1 pulse/cycle
per second.
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.
----------
Ii
----------
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 (IOR)
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.
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
The portion of the backbone cabling within a building. See Backbone Cabling.
Intrinsic
Inherent; within; inside the fiber.
----------
Jj
----------
Jumper
Optical fiber cable that has connectors installed on both ends. See Cable
Assembly.
----------
Kk
----------
kpsi
A unit of force per area expressed in thousands of pounds per square inch;
usually used as the specification for fiber proof test, e.g., 100 kpsi.
Kevlar®
See Aramid Yarn.
Kilometer (km)
One thousand meters, or approximately 3,281 feet, or 0.62 miles. The kilometer
is a standard unit of length measurement in fiber optics. Conversion is
1 ft. = 0.3048 m.
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Ll
----------
LAN
See Local Area Network.
LASER Diode
Light Amplification by Stimulated Emission of Radiation. A laser diode is 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.
Laydown
The first step of fiber manufacturing using the OVD process; deposition
of ultrapure vapors around a rotating target rod to form a glass preform.
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.
Link
A telecommunications circuit between any two telecommunications devices,
not including the equipment connector.
Local Area Network (LAN)
A geographically limited communications network intended for the local transport
of voice, data, and video; often referred to as a customer premises network.
Loose-Tube Cable
Type of cable design whereby coated fibers are encased in buffer tubes offering
excellent fiber protection and segregation.
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Mm
----------
MDPE
Abbreviation used to denote medium density polyethylene; a type of plastic
material used to make cable jacketing.
Macrobend
A large cable bend that can be seen with the unaided eye; often reversible.
Main Cross-Connect (MC)
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.
Mechanical Splicing
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.
Megahertz (MHz)
A unit of frequency that is equal to one million cycles per second.
Meter
3.28 feet.
Microbend
A small, microscopic bend which may be caused by the cabling process; mechanical
stress due to water in the cable during repeated freeze and thaw cycles,
packaging, or installation.
Micrometer (µm)
One millionth of a meter; 10-6 meter; typically used to express the geometric
dimension of fibers, e.g., 62.5 µm.
Minimum Bend Radius
The amount of bend a fiber (or cable) can withstand before experiencing
problems in performance.
Mode
A term used to describe an independent light path through a fiber, as in
multimode or single-mode.
Mode Field Diameter
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.
Modulation
Coding of information onto the carrier frequency. This includes amplitude,
frequency, or phase modulation techniques.
Multifiber Cable
An optical fiber cable that contains two or more fibers.
Multimode Fiber (MM)
An optical waveguide in which light travels in multiple modes; typical core/cladding
sizes (measured in micrometers) are 62.5/125.
Multiplex
Combining two or more signals into a single bit stream that can be individually
recovered.
Multi-User Outlet
A telecommunications outlet used to serve more than one work area, typically
in open-systems furniture applications.
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Nn
----------
National Electrical Code® (NEC)®
An advisory document published by the NFPA and which includes building flammability
requirements for indoor cables.
Note: Local codes take precedence but may refer to or require compliance to the NEC.
Nanometer (nm)
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.
Numerical Aperture (NA)
The number that expresses the light gathering ability of a fiber; related
to acceptance angle or the difference in index of refraction between the core and the cladding.
----------
Oo
----------
Optical Fiber
See Fiber.
Optical Time Domain Reflectometer (OTDR)
An instrument that measures transmission characteristics of optical fiber by sending a series
of short pulses of light down a fiber and providing a graphic representation
of the backscattered light.
Outside Vapor Deposition (OVD)
An optical fiber manufacturing method developed, patented, and used by Corning;
manufacturing method using three steps-laydown, consolidation, and draw.
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Pp
----------
PE
Abbreviation used to denote polyethylene; a type of plastic material used
for outside plant cable jackets.
PVC
Abbreviation used to denote polyvinyl-chloride; a type of plastic material
used for cable jacketing; typically used in flame-retardant cables.
PVDF
Abbreviation used to denote polyvinyl-difluoride; a type of material used
for cable jacketing; often used in plenum-rated cables.
Pigtail
Optical fiber cable that has a connector installed on one end. See Cable
Assembly.
PIN Diode
A semiconductor device used to convert optical signals to electrical signals
in a receiver.
Plenum
An air-handling space such as that found above drop-ceiling tiles or in
raised floors; also, a fire-code rating for indoor cable.
Point-to-Point
A connection established between two specific locations as between two buildings.
Prefusing
A low current electric arc used to clean the fiber end prior to fusion splicing.
----------
Qq
----------
----------
Rr
----------
RH
Relative Humidity.
Receiver
An electronic package that converts optical signals to electrical signals.
Reflectance
Reflectance is the ratio of power reflected to the incident power at a connector
junction or other component 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.
Repeater
A device used to regenerate an optical or electrical signal to allow an increase in the
system length.
Return Loss
See Reflectance.
Riser
Pathways for indoor cables that pass between floors. It is normally a vertical
shaft or space; also a fire-code rating for indoor cable.
----------
Ss
----------
Scattering
The loss of signal power (light) from the fiber core caused by impurities or changes
in the index of refraction of the fiber.
Single-Mode Fiber (SM)
An optical waveguide (or fiber) in which the signal travels in one mode.
The fiber has a small core diameter, typically 8.3 µm.
Splice Closure
A container used to organize and protect splice trays; typically used in
outside plant environments.
Splice Tray
A container used to secure, organize, and protect spliced fibers.
Splicing
The permanent joining of bare fiber ends to another fiber. See Fusion Splice
and Mechanical Splicing.
----------
Tt
----------
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.
Tensile
Pulling (strength or stress).
Termination
A connection.
Tight-Buffered Cable
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.
Total Internal Reflection
Reflection that occurs when a light ray traveling in one material hits another
material and reflects back into the original material without any loss of
light.
Transmitter
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.
----------
Uu
----------
UL
Underwriters Laboratories, Inc.
----------
Vv
----------
Video
Video cameras and cable television.
Visible spectrum
The portion of the electromagnetic spectrum that can be seen by the unaided
human eye.
Voice
Telephone services.
----------
Ww
----------
Wavelength
The distance between two successive points of an electromagnetic waveform,
usually measured in nanometers (nm).
Window
A range of wavelengths within which a fiber best operates.
Work-Area Telecommunications Outlet
A connecting device located in a work area at which the horizontal cabling
terminates and provides connectivity for work-area patch cords.
----------
Xx
----------
----------
Yy
----------
----------
Zz
