Fiber Optics Glossary
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Absorption: Decrease in signal strength in optical fiber as a result of the
conversion of optical light to heat due to impurities in the fiber.
Angled Physical Contact. A fiber optic connector with an angled end used to
lessen back reflection.
A protective coating or jacket for a fiber optic cable
Attenuation: A loss of signal strength within a fiber optic cable, usually
expressed in dB.
Attenuator: A passive component designed to lessen signal strength while
minimizing waveform distortion.
Backreflection (BR): The scattering of optical power within a cable that is
usually caused by a large change to the index of refraction between two points
in the cable.
Bandwidth: The frequency range at which an optical fiber can transmit and
Loss: Signal loss that is caused by bending an optical fiber cable beyond the
manufacturer’s minimum recommended bend radius specification.
Radius: The smallest practical radius that an optic fiber or cable can be bent
prior to reaching an excessive level of attenuation.
Bidirectional: A fiber cable operating in both transmitting and receiving
Any material that is used as a protective coating for a fiber optic cable.
Celsius or Centigrade. Used in manufacturers’ specifications for proper use and
maintenance of a cabling environment.
A structure in which one or more fibers or wires is enclosed, typically with
reinforcement and in a protective jacket.
Assembly: A fiber optic cable that is terminated on both ends with any one of a
number of optical connectors.
Plant: All of the networking components that are used between the transmitter
and the receiver of an optical system.
Chromatic Dispersion: A loss of bandwidth in a fiber optic cable that is caused
by various wavelengths of light traveling at multiple speeds through the cable.
Cladding: The specialized material that coats the core optical material in a
fiber. Cladding features a lower refraction index than the core optical
material which causes the light signal to reflect inward and travel back into
Cleaving: A special process by which an optical fiber is scored to produce a
controlled breaking of the fiber which results in a flat and clean end that is
close to perpendicular to the fiber axis.
Coarse Wavelength Division Multiplexing. This is the process of piling 8 or
less channels within the 1550 nm sector of an optical fiber.
Coating: The various materiala that surround the cladding of an optical fiber
to protect it from environmental damage.
Concatenation: The process of linking multiple pieces of optical fiber.
Concentricity: The measured offset between the center of the optical fiber core
and the center of its cladding in a fiber optic cable. Or the measured offset
between the center of the connector’s ferrule and the center of the connector’s
hole in the ferrule.
Connector: A physical device that offers the connection and/or disconnection
between two fibers or of the fiber and the source or detector).
The inner section of an optical fiber that transmits the light signal.
Coupler: An optical component that either combines or splits a signal between
Decibel. A logarithmic scale measurement unit of relative light power.
Decibels relative to milliwatt.
Detector: An optoelectric component that converts an optical signal into
mismatch loss: Attenuation caused by splicing two different diameter optical
fiber cores. Loss is caused when a light signal is transmitted from the larger
core into the smaller core.
Dielectric: A substance which does not conduct or transmit electrical current.
Dispersion: The spacing out of a light signal in an optical fiber that is
caused by various speed light signals traveling through the fiber. This is
typically caused by either modal or chromatic effects in the fiber.
Dispersion Shifted Fiber. This is a specific type of singlemode fiber that is
designed to have near zero dispersion at 1550 nm.
Window Fiber: This is special fiber that has been optimized to run more than
Cable: This is a cable that has been manufactured with two fibers that
typically allows a fiber optic system to both transmit/receive optical signals.
Dense Wavelength Division Multiplexing. Transmitting multiple, tightly-spaced
wavelengths in the 1550 nm region within a single optical fiber.
Enterprise Systems CONnection. This is a virtually obsolete optical connector
previously utilized for computer to computer data exchange.
Ethernet: This is a Networking Communication Protocol (IEEE 802.3) that has
become the standard for using various transmission media, including LAN, WAN,
Loss: That portion of the light signal that does not make it through the fiber
Extrinsic Loss: Any loss in a fiber optic plant that is not caused by the fiber
Fahrenheit. Used in manufacturers’ specifications for proper use and
maintenance of a cabling environment.
standard type of fiber optic patch cable end connector.
Fiber Distributed Data Interface. This is a type of fiber optical connection
used in local area networking.
Ferrule: This is the component in a fiber optic connector that aligns and also
acts as a terminator for the fiber optic patch cable.
Fiber To The Curb. This is the standard abbreviation used for the fiber optic
service provided to a node that is connected by a coaxial cable to a
neighborhood of nearby homes or buildings.
Fiber To The Home. This is the standard abbreviation used for the fiber optic
service provided to a node located in a home or building.
Fiber Optic Test Procedure. This term refers to the standard procedures
specified by the Electronic Industries Association (EIA) and used for testing
fiber optic systems.
Reflection: This refers to the Reflection loss at the end of a fiber optical
cable that is caused by the difference in the index of refraction between glass
Splicer: This is a special fiber optic instrument that bonds two optical fibers
together via heat and pressure.
Giga. Mathematical prefix representing one billion, as in GigaHertz (one
Germanium. A material often found in detectors and other electronic devices.
Gigahertz. This represents one billion cycles per second.
Index Fiber: This is a type of multimode fiber optic cable in which the
refractive index of the core decreases parabolically as it nears the outer
A wave of one cycle per second.
Fiber Coax (HFC): This is a hybrid cable with both fiber and copper wires used
as media for data transmissions.
Network: This is a data network that utilizes both fiber and copper cables.
Institute of Electrical and Electronics Engineers. This is a nonprofit
association that provides standards for use within the Electrical and
Refraction: The measured ratio of the speed of light in free space versus the
speed of light in a fiber optic strand.
InGaAsP: Indium Gallium Arsenide Phosphide. This is a material that is used in
high performance fiber optic detectors.
Insertion Loss: This is the loss of signal that results when a component (e.g.,
a connector) is inserted into a fiber optic cable pathway.
Interferometer: This is a specialized instrument that is used to measure the
endface geometry of a fiber optic connector.
Intrinsic Loss: This is the loss of signal that occurs in spliced fibers due to
differences in the types of fibers that have been spliced together.
The protective outer covering of a fiber optic cable.
A fiber optic cable assembly with connectors on both ends. Also known as a
KiloHertz. A signal measurement calculated at 1,000 cycles per second.
kilometer. 1,000 meters (1km=3280 ft)
Local Area Network. A data network that exists in a relatively small geographic
Core Fiber: A fiber optic strand with a core of 200 microns or more.
Tube: A type of fiber optic cable in which the fiber strands are situated
within a smaller subunit inside the cable’s jacket.
Usually expressed in Decibels (dB). This refers to the amount of signal strength
that is lost in a fiber optic cable via connectors, splices, the fiber itself,
and other external influences.
Budget: The overall attenuation in a system based upon all signal loss factors.
Mega. Mathematical expression for one million, as in MegaHertz.
milliamp. One one-thousandth of an Amp.
Macrobend: The macroscopic bending of a fiber from a straight line. This can
cause light to leak out from the fiber, causing attenuation.
Metropolitan Area Network. This is used to signify a network that is larger
than a LAN, including a series of connected LAN’s over a wider metropolitan
Splicing: This refers to the splicing together of many optical fibers into a
Mechanical Splice: This refers to a specific fiber splicing application in
which two optical fibers are joined together via mechanical means.
Megahertz. This represents 1,000,000 Hertz or 1,000,000 cycles per second.
Microbend: This refers to the mechanical stress placed on a fiber optic strand
that causes signal loss.
Bend Radius: This refers to the smallest radius that an optical cable can be
bent orior to causing an increase in attenuation.
Multimode. A type of fiber optic cable which allows multiple signal waves to
travel on it simultaneously.
The ability of an electromagnetic wave or signal to travel in a fiber.
Field Diameter: This is the measurement of the distribution of optical signal
strength in a singlemode fiber.
Filter: This is a device that eliminates higher-order modes from a fiber optic
Stripper: This is a specialized component that eliminates modes traveling in
Multimode (MM) Fiber: This is an optical fiber that allows more than one signal
to be transmitted simultaneously.
Numerical Aperture: This refers to the light-gathering ability of a fiber optic
strand and reflects the largest angle of acceptance as measured against the
fiber axis. It may also refer to the spread of the light signal from the end of
a fiber strand.
Optical to Electrical Converter. This is a component that is used to convert
optical signals to electrical signals.
Fiber: A glass or plastic fiber that has the ability to act as a waveguide for
light for the transmission of data.
Link Loss Budget: This refers to maximum loss allowed in a fiber optic link
before network performance suffers.
Power Meter: This is an instrument that is used to measure the optical signal
strength at the end of a fiber optic cable.
Return Loss: This is the calculation of the ratio of optical power reflected
from a device back to the light source and is usually expressed in decibels.
Time Domain Reflectometer: This is a specialized instrument that is used to
measure both the loss and the reflections that occur in a fiber link.
This is a type of connector polish that allows fiber optic strand ends to
contact the connector while reducing back reflection and insertion loss.
Pigtail: A length of fiber optic cabling with a connector on only one end.
Waveguide: This refers to a waveguide that is made with a dielectric material.
Planar Lightwave Circuit. This is a device that incorporates a planar
Cable (UL type OFNP): This is a specially jacketed cable whose smoke and
flammability characteristics meet building code requirements thereby allowing it
to be run in areas where a fire hazard may exist.
Passive Optical Network. This refers to a network that features fiber optic
cabling in either all or most of the network servicing the end user.
Preform: A manufacturer’s glass rod that has specific attributes so that
optical fiber strands may be drawn from it.
Radiation-hardened Fiber: This refers to a specialized type of fiber optic
cablethat can recover most of performance capabilities after exposure to
Scattering: This refers to the scattering of light that is caused by small
imperfections along the length of the fiber optic strands.
Receiver: This is a device that contains a detector and converts light signals
to electrical signals.
Cable: This is a specially manufactured cable in which multiple fibers are
manufactured in a flat ribbon-like cable construction.
(Storage Area Network): This refers to one or more shared storage devices that
are networked so that the storage device(s) is available to all servers on a WAN
type of fiber optical cable connector. The “SC” stands for “Subscription
This refers to the jacket or outer protective layer of the fiber optic patch
Silicon, a material used in certain multimode detectors.
Singlemode: This refers to the type of optical fiber which only supports a
single lightwave propagating through it.
optical fiber connector component.that is mostly obsolete in modern networks.
This refers to the joining of two optical fibers for the purposes of providing a
continuous waveguide for a fiber optic signal.
Ratio: This number specifies the actual calculation of power distribution
within an optical coupler.
type of fiber optical cable connector.
Step-index Fiber: This refers to a specific type of optical fiber which offers
a consistent refractive index in the actual core of the fiber while also
offering a significant decrease in refractive index in the cladding of the
Member: This is a physical element that is incorporated into a fiber optic
cable structure to add tensile strength.
Throughput Loss: The comparison of signal strength at the output port of a
fiber optic coupler versus the power measured at the input port.
Throughput Port: The out put port in a fiber optic coupler..
Buffer: The specialized material that surrounds and protects the optical fiber
strand(s) in a fiber optic cable.
Internal Reflection: The phenomenon that occurs when the lightwave in an
optical fiber core strikes the cladding at a larger angle than the critical
Transmitter: An optical network component that converts electrical signals to
Unidirectional: The quality of only operating in a single direction.
Abbreviation for Volt.
Abbreviation for Watt.
Wide Area Network. This refers to a data communications network that
encompasses a broad geographic area.
Waveguide: This is a dielectric material in which the optical structure has an
inner core with a higher index of refraction than the outer section, thereby
guiding lightwaves through the inner core via the principle of total internal
Wavelength Division Multiplexing: This communications technique allows for the
utilization of a single optical fiber strand to send several signals through the
strand with each signal operating at different wavelengths.
Wideband: The quality of a device or network having a large bandwidth.
This refers to a situation in which two cables connected by their outer
protective jackets so that they may be quickly and easily separated along part
or all of their lengths by simply physically pulling them apart.
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