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The following terms are defined within the context
of the fiber optics industry.
Acceptance Angle
The halfangle of the cone within which incident
light is totally internally reflected by the fiber core.
It is equal to Arcsin (NA).
Amplitude Modulation (AM)
A transmission technique in which the amplitude of
the carrier is varied in accordance with the signal.
A means of signal transmission whereby transmitter (light
source) signal intensity is varied in relation to the
amplitude of the input signal.
Analog
A format that uses continuous physical variables such
as voltage amplitude or frequency variations to transmit
information.
Angle of Incidence
The angle between an incident ray and the normal to
a reflecting surface.
Aramid Yarn
Strength element used in Siecor cable to provide
support and additional protection of the fiber bundles.
Kevlar is a particular brand of aramid yarn.
Armoring
Additional protection between jacket layers that
provides protection against severe outdoor environments.
Usually made of plasticcoated steel, and may
be corrugated for flexibility.
Attenuation
(1) Limited Operation The condition in a fiber optic
link when operation is limited by the power of the
received signal (rather than by bandwidth or by distortion).
(2) The decrease in magnitude of power of a signal
in transmission between points. A term used for expressing
the total losses on an optical fiber consisting of
the ratio of light output to light input. Attenuation
is usually measured in decibels per kilometer (db/km)
at a specific wavelength. The lower the number, the
better the fiber. Typical multimode wavelengths
are 850 and 1300 nanometers (nm); singlemode, at 1300
and 1500 nm. NOTE: When specifying attenuation, it
is important to note if it is nominal or average,
room temperature, value or maximum over operating
range.
Attenuator
A passive optical component that intentionally reduces
the optical power propagating in a fiber.
APD (Avalanche Photodiode)
A photodiode designed to take advantage of avalanche
multiplication of photocurrent. As the reversebias
voltage approaches the breakdown voltage, holeelectron
pairs created by absorbed photons acquire sufficient
energy to create additional holeelectron pairs
when they collide with ions; thus a multiplication
or signal gain is achieved.
Average Power
The average level of power in a signal that varies
with time.
Axial Ray
A light ray that travels along the axis of an optical
fiber.
B.P.S. (Bits Per Second)
The number of energy pulses passing a given point
in a transmission medium in one second.
Backscattering
A small fraction of light that is deflected out of
the original direction of propagation by scattering
suffers a reversal of direction. In other words, it
propagates in the optical waveguide towards the transmitter.
Bandpass
A range of wavelengths over which a component will
meet specifications.
Bandwidth Limited Operation
The condition prevailing when the system bandwidth,
rather than the amplitude of the signal, limits performance.
The condition is reached when modal dispersion distorts
the shape of the waveform beyond specified limits.
Bandwidth
Information carrying capacity of an optical fiber.
Expressed in MHzkm, specifies the analog bandwidth
capability or number of digital transitions per second
the fiber can sustain over a 1 km distance. Bandwidth
is dependent upon wavelength and type of light source.
Baseband
A method of communication in which a signal is transmitted
at its original frequency without being impressed
on a carrier.
BAUD
A unit of signaling speed equal to the number of
signal intervals per second, which may or may not
be equal to the data rate in bits per second. In some
encoding schemes, such as Non Return to Zero (NRZ).
equals data rate. In others, such as Manchester encoding,
two transitions per bit are required.
Beamsplitter
A device used to divide an optical beam into two
or more separate beams.
Bend Radius
Radius a fiber can bend before the risk of breakage
or increase in attenuation. Also can refer to cable
bend radius.
Bend Loss
A form of increased attenuation in a fiber that results
from bending a fiber around a restrictive curvature
(a macrobend) or from minute distortions.
BEND RADIUS
The lower limit below which fiber or cable should
not be bent for reasons of optical and mechanical
performance.
BER
Bit error rate. Specifies expected frequency of errors.
The ratio of incorrectly transmitted bits to correctly
transmitted bits.
Bit
A binary digit, the smallest element of information
in binary system. A 1 or 0 of binary data.
BreakOut Cable
See FanOut Cable.
Broadband
The ability of a system to carry a multitude of signals
simultaneously. In data transmission, it denotes transmission
facilities capable of handling frequencies greater
than those required for highgrade voice communications.
The higher frequency allows the carrying of several
simultaneous channels. Broadband infers the use of
a carrier signal rather than direct modulation (i.e.,
baseband).
BUFFER
The protective coating over a fiber. The primary
buffer (i.e., next to the cladding) is 250 microns
in diameter. A secondary buffer of 900 micron diameter
is used on indoor cables.
Buffered Fiber
Fiber protected with an additional material (hytrel
or nylon) to provide ease in handling, connectorization
and increased tensile strength.
Buffering
(1) A protective material extruded directly on the
fiber coating to protect it from the environment;
(2) Extruding a tube around the coated fiber to allow
isolation of the fiber from stresses on the cable.
Building Entrance
Terminal Cable entrance point where typically a trunk
cable between buildings is terminated and fiber is
then distributed through the building.
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.
Bus Network
A network topology in which all terminals are attached
to a transmission medium serving as a bus.
BUS
Commonly called '"data bus"", term
used to describe the physical linkage between stations
on a network sharing some common communication.
Byte
A unit of 8 bits (Digital Data).
Cable
An assembly of optical fibers and other material
providing mechanical and environmental protection
and optical insulation of the waveguides.
Cable Assembly
Fiber optic cable that has connectors installed on
one or both ends. General use of these cable assemblies
includes the interconnection of multimode and
singlemode fiber optical cable systems and optoelectronic
equipment. If connectors are attached to only one
end of the cable, it is known as a pigtail. If connectors
are attached to both ends, it is known as a jumper.
Cable Bend Radius
Cable bend radius during installation infers that
the cable is experiencing a tensile load. Free bend
infers a lower allowable bend radius since it is at
a condition of no load.
Carrier Sense Multiple Access
With Collision Detection (CSMA/CD)
A technique used to control the transmission channel
of a local area network to ensure that there is no
conflict between terminals that wish to transmit.
Center Wavelength(s)
The nominal operating wavelength(s).
Central Member
The center component of a cable. It serves as an
antibuckling element to resist temperatureinduced
stresses. Sometimes serves as a strength element.
The central member is composed of steel, fiberglass,
or glassreinforced plastic.
Central Office (CO)
The place where communications common carriers terminate
customer lines and locate switching equipment that
interconnects those lines.
Channel
A communications path or the signal sent over that
channel. Through multiplexing several channels, voice
channels can be transmitted over an optical channel.
Chromatic Dispersion
Spreading of a light pulse caused by the difference
in refractive indices at different wavelengths.
Cladding
The material surrounding the core of an optical fiber.
The cladding must have a lower index of refraction
in order to steer the light in the core.
Cladding Mode
A mode confined to the cladding; a light ray that
propagates in the cladding.
Coating
A material put on a fiber during the drawing process
to protect it from the environment.
Conduit
Pipe or tubing through which cables can be pulled
or housed.
Connector
A mechanical device used to align and join two fibers
together to provide a means for attaching and decoupling
it to a transmitter, receiver or another fiber. Commonly
used connectors include the FC, FCPC, Biconic, ST
ConnectorCompatible, D4, SMA 905 or 906.
Core
The central region of an optical fiber through which
light is transmitted.
Core Eccentricity
A measure of the displacement of the center of the
core relative to the cladding center.
Coupler
(1) A passive device that distributes optical power
among two or more ports. (Can be in various ratios.)
Commonly called a splitlet. (2) A multipod device
used to distribute optical power.
COUPLER
An optical device that coupes (or splits) light in
accordance with its number of input and output legs.
Coupling Efficiency
The efficiency of optical power transfer between
two components.
Coupling Ratio
The percentage of light transferred to a receiving
output port with respect to the total power of all
output ports.
Coupling Loss
The power loss suffered when coupling light from
one optical device to another
CPC
Customer Premises Communication
CPE
Customer Premises Equipment
Critical Angle
The smallest angle from the fiber axis at which a
ray may be totally reflected at the core/cladding
interface.
Cutoff Wavelength
The shortest wavelength at which only the fundamental
mode of an optical waveguide is capable of propagation.
Data Rate
The maximum number of bits of information which can
be transmitted per second, as in a data transmission
link. Typically expressed as megabits per second (mb/s).
dbm Decibel referenced to a milliwatt. dbp Decibei
referenced to a microwatt.
Decibel (dB)
Unit for measuring the relative strength of a signal.
Power level referenced in decibels to a microwatt.
Demultiplex
The process of separating optical channels.
Detector
(1) A transducer that provides an electrical output
signal in response to an incident optical signal.
The current is dependent on the amount of light received
and the type of device. (2)A semiconductor device
which converts optical energy to electrical energy.
DiameterMismatch Loss
The loss of power at a joint that occurs when the
transmitting half has a diameter greater than the
diameter of the receiving half. The loss occurs when
coupling light from a source to fiber, from fiber
to fiber, or from fiber to detector.
Dielectric
Nonmetallic and, therefore, nonconductive.
Glass fibers are considered dielectric. A dielectric
cable contains no metallic components.
Digital
A data format that uses two physical levels to transmit
information. A discrete or discontinuous signal.
Direetivity
Also referred to as nearend crosstalk, it is
the amount of power observed at a given input port
with respect to an initial input power.
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: (a) mode dispersion
caused by differential optical path lengths in a multimode
fiber; (b) material dispersion caused by a differential
delay of various wavelengths of light in a waveguide
material; and (c) waveguide dispersion caused by light
traveling in both the core and cladding materials
in singlemode fibers.
DistortionLimited Operation
Generally synonymous with bandwidthlimited
operation.
Duplex Cable
A twofiber cable suitable for duplex transmission.
Duplex Transmission
Transmission in both directions, either one direction
at a time (half duplex) or both directions simultaneously
(full duplex).
Duty Cycle
In a digital transmission, the ratio of high levels
to low levels.
EIA
Electronic Industries Association. A standards association
that publishes test procedures. See FOTP.
Electromagnetic Interference
(EMI)
Any electrical or electromagnetic interference that
causes undesirable response, degradation, or failure
in electronic equipment. Optical fibers neither emit
nor receive EMI.
EMD
Equilibrium Mode Distribution.
ENCODING
A scheme to represent digital ones and zeros through
combining high and low signal voltage states.
Excess Loss
(1) In a fiberoptic coupler, the optical loss
from that portion of light that does not emerge from
the nominally operational pods of the device. (2)The
ratio of the total output power of a passive component
with respect to the input power.
Extrinsic Loss
In a fiber interconnection, that portion of loss
that is not intrinsic to the fiber but is related
to imperfect joining, which may be caused by the connector
or splice.
FanOut Cable
Multifiber cable constructed in the tight buffered
design. Designed for ease of connectorization and
rugged applications for intra or interbuilding
requirements.
Ferrule
A small alignment tube attached to the end of the
fiber and used in connectors. Generally made of stainless
steel, alumina, or zirconia, used to confine and align
the stripped end of a fiber.
Fiber Optic Link
Any optical fiber transmission channel designed to
connect two end terminals or to be connected in series
with other channels.
Fiber
Thin filament of glass. An optical waveguide consisting
of a core and a cladding which is capable of carrying
information in the form of light.
Fiber Optics
Light transmission through optical fibers for communication
or signalling.
FOTP
Fiber Optic Test Procedures
FOTS
Fiber Optic Transmission System
FREQUENCY MODULATION (FM)
Transmission scheme whereby information is sent by
varying the frequency of an optical carrier. A method
of transmission in which the carrier frequency varies
in accordance with the signal.
Fresnel Reflection
The reflection of a portion of the light incident
on a planar surface between two homogeneous media
having different refractive indices. Fresnel reflection
occurs at the air/glass interfaces at entrance and
exit ends of an optical fiber.
Fundamental Mode
The lowest order mode of a waveguide.
Fusion Splicing
A permanent joint accomplished by the application
of localized heat sufficient to fuse or melt the ends
of the optical fiber, forming a continuous single
fiber.
FUSION SPLICE
A joining of two fibers by physically fusing through
heat the two fiber ends.
Gap Loss
Loss resulting from the end separation of two axially
aligned fibers.
GradedIndex
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 high bandwidth capabilities.
GroundLoop Noise
Noise that results when equipment is grounded at
ground points having different potentials and thereby
created an unintended current path. The dielectric
of optical fibers provide electrical isolation that
eliminates ground loops.
Hard Clad Silica
A fiber with a hard plastic cladding surrounding
a silica glass core.
IEEE
Institute of Electrical and Electronics Engineering.
Index Matching Material
A material, often a liquid or cement whose refractive
index is nearly equal to the core index, used to reduce
Fresnel reflections from a fiber end face.
Index of Refraction
The ratio of light velocity in a vacuum to its velocity
in a given transmitting medium.
Index Profile
Curve of the refractive index over the cross section
of an optical waveguide.
INDEX OF REFRACTION
An optical characteristic (n) of a material, referencing
the speed of light in that material to a vacuum.
Insertion Loss
The attenuation caused by the insertion of an optical
component; in other words, a connector or coupler
in an optical transmission system.
Isolation
Also referred to as farend crosstalk
or farend isolation. Predominantly used in reference
to WDM products, it is a measure of light at an undesired
wavelength at any given port.
Jumper
Fiber optic cable that has connectors installed on
both ends. See also cable assembly.
JUMPER
A section of cable with a connector an both ends.
Kevlar
See Aramid Yarn
Kilometer
One thousand meters or 3,281 feet. The kilometer
is a unit of measurement for fiber optics.
KPSI
A unit of tensile strength expressed in thousands
of pounds per square inch.
LASER Light
Amplification by Stimulated Emission of Radiation.
A device which produces coherent light with a narrow
range of wavelengths.
Lateral Displacement Loss
The loss of power that results from lateral displacement
from optimum alignment between two fibers or between
a fiber and an active device.
Launch Angle
Angle between the propagation direction of the incident
light and the optical axis of an opticat waveguide.
Launching Fiber
A fiber used in conjunction with a source to excite
the modes of another fiber in a particular way. Launching
fibers are most often used in test systems to improved
the precision of measurements.
Light
In the laser and optical communication fields, the
portion of the electromagnetic spectrum that can be
handled by the basic optical techniques used for the
visible spectrum extending from the near ultraviolet
region of approximately 0.3 micron, through the visible
region and into the midinfrared region of about
30 microns.
LED (Light Emitting Diode)
A device used in a transmitter to convert information
from electric to optical form. It typically has a
large spectral width.
LIGHT EMITTING DIODE (LED)
A semiconductor diode which emits light when forward
biased to an optical signal.
Lightguide Cable
An optical fiber, multiple fiber, or fiber bundle
which includes a cable jacket and strength
Lightwaves
Electromagnetic waves in the region of optical frequencies.
The term "light" was originally restricted
to radiation visible to the human eye, with wavelengths
between 400 and 700 nanometers (nm). However, it has
become customary to refer to radiation in the spectral
regions adjacent to visible light (in the near infrared
from 700 to about 2000 nm) as "light" to
emphasize the physical and technical characteristics
they have in common with visible light.
Link
A fiber optic cable with connectors attached to a
transmitter (source) and receiver (detector).
LLDPE
Linear Low Density Polyethylene jacketing.
Local Area Network (LAN)
A geographically limited communications network intended
for the local transport of data, video and voice.
Loose Tube
A protective tube loosely surrounding a cabled fiber,
often filled with a water blocking gel.
LOOSE TUBE
Type of cable design, primarily for outdoor use,
where one or more fibers are enclosed in hard plastic
tubes. Fibers are usually buffered to 250 microns.
Loss
Attenuation of optical signal, normally measured
in decibels.
Macrobending
Macroscopic axial deviations of a fiber from a straight
line, in contrast to microbending.
Material Dispersion
The dispersion associated with a nonmonochromatic
light source due to the wavelength dependence of the
refractive index of a material or of the light velocity
in this material.
MDPE
Medium Density Polyetheylene jacketing.
Mechanical Splicing
Joining two fibers together by mechanical means to
enable a continuous signal. Elastomeric splicing is
one example of mechanical splicing.
Megahedz (MHz)
A unit of frequency that is equal to one million
hertz.
Microbending
Curvatures of the fiber which involve axial displacements
of a few micrometers and spatial wavelengths of a
few millimeters. Microbends cause loss of light and
consequently increase the attenuation of the fiber.
Micron (um)
Another term for micrometer. One millionth of a meter.
10exp6 meter.
Misalignment Loss
The loss of power resulting from angular misalignment,
lateral displacement, and end separation.
Modal Dispersion
Pulse spreading due to multiple light rays traveling
different distances and speeds through an optical
fiber.
Mode Field Diameter (MFD)
The diameter of optical energy in a singlemode fiber.
Because the MFD is greater than the core diameter,
MFD replaces core diameter as a practical parameter.
Mode Filter
A device used to remove highorder modes from
a fiber and thereby simulate EMD.
Mode Scrambler
A device composed of one or more optical fibers in
which strong mode coupling occurs. Frequently used
to provide a mode distribution that is independent
of source characteristics.
Mode
A term used to describe a light path through a fiber,
as in multimode or singlemode.
Mode Mixing
The numerous modes of a multimode fiber differ
in their propagation velocities. As long as they propagate
independently of each other, the fiber bandwidth varies
inversely with the fiber length due to multimode
distortion. As a result of inhomogenejties of the
fjber geometry and of the index profile, a gradual
energy exchange occurs between modes with differing
velocities. Due to this mode mixing, the bandwidth
of long multimode fibers is greater than the value
obtained by linear extrapolation from measurements
on shod fibers.
MODE
A light path through a fiber.
Modulation
Coding of information onto the carrier frequency.
This includes amplitude, frequency, or phase modulation
techniques.
Monochromatic
Consisting of a single wavelength. In practice, radiation
is never perfectly monochromatic but, at best, displays
a narrow band of wavelengths.
MultiMode Fiber
An optical waveguide in which light travels in multiple
modes. Typical core/cladding sizes (measured in microns)
are 50/125, 62.5/125, and 100/140.
MULTIMODE FIBER
A fiber type which supports multiple light paths
through its core.
MULTIPLEX
The combination of several signals onto a single
communications channel.
Multiplexing
The process by which two or more signals are transmitted
over a single communications channel. Examples include
timedivision multipiexing and wavelengthdivision
multiplexing.
NAMismatch Loss
The loss of power at a joint that occurs when the
transmitting half has an NA greater than the NA of
the receiving half. The loss occurs when coupling
light from a soume to fiber, from fiber to fiber,
or from fiber to detector.
Nanometer
A unit of measurement equal to one billionth of a
meter. 10exp9 meter.
NANOMETER
Common unit of measure for wavelength One billionth
of a meter.
NEC
National Electrical Code. Defines building flammatory
requirements for indoor cables.
Numerical Aperture
A numerical value that expresses the light gathering
ability of a fiber.
Numerical Aperture (NA)
The number that expresses the light gathering power
of a fiber.
NUMERICAL APERTURE
The imaginary cone which defines the acceptance area
for the fiber core to accept rays of light.
Optical Time Domain Reflectometer
(OTDR)
A method for characterizing a fiber wherein an optical
pulse is transmitted through the fiber and the resulting
backscatter and reflections to the input are measured
as a function of time. Useful in estimating attenuation
coefficient as a function of distance and identifying
defects and other localized losses.
Optical Fiber
See Fiber.
Optical Waveguide
Dielectric waveguide with a core consisting of optically
transparent material of low attenuation (usually silica
glass) and with cladding consisting of optically transparent
material of lower refractive index than that of the
core. It is used for the transmission of signals with
lightwaves and is frequently referred to as fiber.
In addition, there are planar dielectric waveguide
structures in some optical components, such as laser
diodes, which are also referred to as optical waveguides.
Optical Waveguide
See Fiber.
Optoelectronic
Pertaining to a device that responds to optical power,
emits or modifies optical radiation, or utilizes optical
radiation for its internal operation. Any device that
functions as an electricaltooptical or opticaltoelectrical
transducer.
OTDR
Optical time domain Reflectometer. A test instrument,
working on the principal of continuous energy backscatter,
which provides a complete characterization of fiber
loss along its length
PCM
PulseCoded Modulation.
PCS
PlasticClad Silica.
PE
Abbreviation used to denote polyethylene. A type
of plastic material used to make cable jacketing.
Peak Wavelength
The wavelength at which the optical power of a source
is at a maximum.
Photocurrent
The current that flows through a photosensitive device,
such as a photodiode, as the result of exposure to
radiant power.
Photodetector
An optoelectronic transducer, such as a pin photodiode
or avalanche photodiode.
Photodiode
A diode designed to produce photocurrent by absorbing
light. Photodiodes are used for the detection of optical
power and for the conversion of optical power into
electrical power.
Photon
A quantum of electromagnetic energy.
Pigtail
Fiber optic cable that has connectors installed on
one end. See also Cable Assembly.
PIN Photodiode
A diode with a large intrinsic region sandwiched
between pdoped and ndoped semiconducting regions.
Photons in this region create electron hole pairs
that are separated by an electric field thus generating
an electric current in the load circuit.
Plastic Fiber
An optical fiber having a plastic core and plastic
cladding.
PlasticClad Silica Fiber
An optical fiber having a glass core and plastic
cladding.
Plenum
Air duct inside buildings through which cable can
be pulled or housed.
Plenum Cable
A cable whose flammability and smoke characteristics
allow it to be routed in a plenum area without being
enclosed in a conduit.
PointtoPoint
A connection established between two specific locations,
as between two buildings.
Polarization Stability
The variation in insertion loss as the polarization
state of the input light is varied.
Preform
A glass structure from which an optical fiber waveguide
may be drawn.
Prefusing
Fusing with a low current to clean the fiber end.
Precedes fusion splicing.
Primary Coating
The plastic coating applied directly to the cladding
surface of the fiber during manufacture to preserve
the integrity of the surface.
Pulse Spreading
The dispersion of an optical signal with time as
it propagates through an optical fiber.
PUR
Polyurethane. Material used in manufacture of a type
of jacketing material.
PVC
Polyvinyl Chloride. Material used in manufacture
of a type of jacketing material.
Receiver
An electronic package which converts optical signals
to electrical signals.
Receiver Sensitivity
The optical power required by a receiver for low
error signal transmission. In the case of digital
signal transmission, the mean optical power is usually
quoted in Watts or dbm (decibels referred to 1 milliwatt).
Reflectance
Light that is reflected back along the path of transmission,
from either the coupling region, the connector or
a tertninated fiber..
Reflection
The abrupt change In direction of a light beam at
an interface between two dissimilar media so that
the light beam returns into the media from which it
originated.
Refraction
The bending of a beam of light at an interface between
two dissimilar media or a medium whose refractive
index is a continuous function of position (graded
index medium).
Refractive Index
See Index of Refraction.
Regenerative Repeater
A repeater designed for digital transmission that
both amplifies and reshapes the signal.
Repeater
A device which consists of a transmitter and a receiver
or transceiver, used to regenerate a signal to increase
the system length.
Return Loss
See reflectance.
Ring Network
A network topology in which terminals are connected
in a pointtopoint serial fashion in an unbroken
circular configuration.
Rise Time
The time it takes the signal output to rise from
low levels to peak value. Usually measured from 10%
to 90% of max. output.
Riser
Application for indoor cables that pass between floors.
It is normally a. vertical shaft or space.
Scattering
A property of glass which causes light to deflect
from the fiber and contributes to losses.
Sensitivity
For a fiberoptic receiver, the minimum optical
power required to achieve a specified level of performance,
such as a BER.
SENSITIVITY
The minimum amount of energy required by a receiver
for successful operation.
SignaltoNoise Ratio
(SNR)
The ratio of signal power to noise power.
SIGNALNOISE RATIO
The ratio of signal power to noise power. Measured
in dB.
Simplex Cable
A term sometimes used for a singlefiber cable.
Simplex Transmission
Transmission in one direction only.
SingleMode Fiber
An optical waveguide (or fiber) in which the signal
travels in one "mode". The fiber has a small
core diameter.
SINGLEMODE FIBER
A fiber type which supports a single path through
its core, Wavelength dependent.
SMA
A connector type with screw threads,
Source
The means used to convert an electrical information
carrying signal to a corresponding optical signal
for transmission by fiber. The source is usually a
Light Emitting Diode (LED) or Laser.
Spectral Width
A measure of the extent of a spectrum. For a source,
the width of wavelengths contained in the output at
one half of the wavelength of peak power. Typical
spectral widths are 20 to 60 nm for an LED and 2 to
5 nm for a laser diode.
SPECTRAL WIDTH
The width of wavelengths in a light pulse, based
on 50% intensity.
Splice Closure
A container used to organize and protect splice trays.
Splice Tray
A container used to organize and protect spliced
fibers.
Splice
(1)A permanent joint between two optical waveguides.
(2)Means for joining two fiber ends,
Splicing
The permanent joining of fiber ends to identical
or similar fibers, without the use of a connector.
See also Fusion Splicing and Mechanical Splicing.
Splitting Loss
See coupling ratio.
ST
A connector type with a bayonet housing which is
spring loaded "ST" stands for "straight
tip".
Star Coupler
An active or passive device where energy presented
at an input port is distributed through several output
ports.
Star Network
A network in which all terminals are connected through
a single point, such as a star coupler.
StepIndex
Fiber Optical fiber which has an abrupt ("step")
change in its refractive index, due to a core and
cladding that have different indices or refraction.
Typically used for single mode.
Strength Member
That part of a fiber optic cable composed of Kevlar
aramid yarn, steel strands, or fiberglass filaments
that increase the tensile strength of the cable.
Tap Loss
In a fiber optic coupler, the ratio of power at the
tap port to the power at the input port.
Tap Port
In a coupler in which the splitting ratio between
output pods is not equal, the output port containing
the lesser power.
Tee Coupler
A ThreePod Optical Coupler.
Thermal Stability
A measure of insertion loss variation as the device
undergoes various environmental changes.
Tight Buffer
Type of cable construction whereby each glass fiber
is tightly buffered by a protective thermoplastic
coating to a diameter of 900 microns. High tensile
strength rating achieved, providing durability, ease
of handling and ease of connectorization.
TimeDivision Multiplexing
(TDM)
A transmission technique whereby several lowspeed
channels are multiplexed into a highspeed channel
for transmission.
Topology
The physical layout of a network.
Total Internal Reflection
Total reflection of light back into a material when
it strikes the interface of a material having a lower
index at an angle below the critical angle.
Transceiver
An electronic device which has both transmit and
receive capabilities.
Transducer
A device for converting energy from one form to another,
such as optical energy to electrical energy.
Transmission Loss
Total loss encountered in transmission through a
system.
Transmitter
An electronic package which converts an electrical
signal to an optical signal.
Tree Coupler
A passive fiber optical component in which power
from one input is distributed to more than two output
fibers.
UL
Underwriters Laboratories, Inc.
Uniformity
The maximum insertion loss difference between ports
of a coupler.
Waveguide
Structure that guides electromagnetic waves along
its length. An optical fiber is an optical waveguide.
Wavelength Division Multiplexing
(WDM)
Simultaneous transmission of several signals in an
optical waveguide at differing wavelengths.
Wavelength
The distance between two crests of an electromagnetic
waveform.
Wavelength Dependence
The variation in an optical parameter caused by a
change in the operating wavelength.
WAVELENGTH DIVISION MULTIPLEXING
(WDM)
The process of using multiple wavelengths to carry
multiple signals on a single fiber.
WAVELENGTH
The distance between two peaks on an electromagnetic
waveform
WDM
Wavelength Division Multiplexer a passive fiber
optical device used to separate signals of different
wavelengths carried on one fiber.
WICWavelength Independent Coupler.
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