Fiber Optic Glossary of Terms

Absorption
The absorbing of light energy and conversion to heat, caused by impurities in the glass

Acceptance Angle
The largest angle where the fiber core can accept incoming light, and usually measured from the fiber axis

Access Network
A component within a wider telecommunication network that connects individuals and business users

Adapter
A mechanical device used to align and join fiber optic connectors

Adapter Sleeve
A mechanical fixture contained in an adapter that aligns and holds the terminated fiber connectors; also known as a split sleeve

Aerial Plant
Cables that is suspended in the air on telephone and utility poles

Angled Physical Contact (APC)
A style of fiber optic ferrule polishing with a 5-15 angle on the ferrule tip for the purpose of minimizing backreflection

Angular Misalignment
The angle misalignment of fiber optic connectors, and causes attenuation

Armor
A metallic protective layer inside a fiber optic cable that provides extra protection of the fiber

Armored Cable
A type of fiber optic cable that includes armor

Attenuation
The reduction of optical power between two points and normally expressed in decibels (dB)

Attenuation Coefficient
The attenuation with respect to a specific unit length, usually decibels per kilometer (db/km)

Attenuation Meter
A device used to measure attenuation in fiber optic cables, connectors, and systems

Attenuator
A passive device that reduces the amplitude of a light signal

Average Power
The average power signal over a period of time

Axis
The center of an optical fiber

Backbone
A main portion of a telecommunication network that connects relatively distant points or regions

Backbone Cabling
The cabling in inter- and intra-buildings that connects entrance facilities, equipment rooms and telecommunication closets

Backreflection
Light that is reflected and travels back to the origin source; also known as return loss

Backscattering
Scattering of light and heads in the direction of the original source

Bandwidth
The capacity of an optical fiber in terms of its ability to carry information, and measured in megahertz per kilometer (MHz-km) or gigahertz per kilometer (GHz-km)

Bend Radius
The maximum radius from bending a fiber without significant attenuation or breakage of the fiber

Bending Loss
The attenuation or loss in an optical fiber caused by bending

Bragg Scattering
Scattering of light that is caused by changes in the refractive index of a material

Breakout
Separation of individual fibers or buffer tubes in a fiber optic cable for the purpose of splicing or installing fiber optic connectors

Breakout Cable
A type of fiber optic cable that contains fibers with individual jackets and then all individual jackets surrounded by one common cable jacket

Buffer
The protective layer inside a fiber optic cable that surrounds the fiber cladding that provides protection and mechanical isolation; also known as buffer tubes, buffer coating or coating

Bundle
A group of individual fibers assembled in an unit

Cable
An assembly of optical fibers along with other materials for protecting the fiber, enclosed for protective covering

Cable Assembly
The assembling of fiber optic connectors into fiber optic cables, either in the form of patch cords (connectors on both ends) or pigtails (connector on one end)

Central Member
The center component of a fiber optic cable that can serve as a strength member and therefore also known as central strength member

Channel
A communications path

Channel Spacing
The allocation of bandwidth to channels

Chromatic Dispersion
Dispersion caused by different wavelengths in the light signal travelling at different speeds, expressed in picoseconds per kilometer per nanometer, and the sum of material and waveguide dispersion

Cladding
A layer of glass surround the fiber core in a fiber optic cable, and together with the fiber core make up an optical waveguide

Cleave
A process in fiber optic cable assembly that separating an optical fiber by a controlled fracture of the glass, for the purpose of obtaining a fiber end that is flat, smooth, and perpendicular to the fiber axis

Cleaver
A precision tool that breaks the fiber to produce a flat end for polishing or splicing

Composite Cable
A cable consisting of both fiber and copper; also known as hybrid cable

Concentricity
The measurement of how centered the core is within the cladding

Conduit
Pipes or tubes where fiber optic cables can be pulled or housed

Connector
A mechanical device mounted on an end of a fiber optic cable for the purpose of attaching and decoupling the fiber to another source

Connectorization
The preparation of an end of a fiber and connector assembling; also referred as termination

Containerized Data Center
Data center that is housed in a shipping container, opposed to a building

Core
The center of the optical fiber that transmit light

Coupler
A device that combines light into one fiber or splits light into more than one fiber

Coupling
The transfer of light into or out of an optical fiber

Crimper
A tool that crimps a fiber optic connector to the fibers in the cable to provide additional mechanical strength

Critical Angle
The smallest angle of light ray with respect to the normal that can guide light path

Cross-connect
A facility enabling the termination of cables as well as their interconnection or cross-connection with other cabling or equipment. Also known as a distributor

Customer Premises Equipment (CPE)
Telecommunications equipment located inside customer's premises

Cutoff Wavelength
The wavelength beyond which singlemode fiber only supports one mode of propagation

Decibel (dB)
A measuring unit used to measure optical power

Dielectric
A material such as fiber that is non-metallic and non-conductive

Dispersion
The spreading of light pulses as it travels along the fiber

Dispersion Compensation
The reduction of dispersion in a fiber

Ducting
A conduit for placing and protecting fiber optic cables

Duplex Cable
A type of cable construction where two cables are attached to form one cable

Eccentricity
A measurement of the amount by which the core is not placed centrally in the cladding

Electromagnetic Interference (EMI)
The interference of signal transmission because of radiation; optical fibers are not susceptible to electromagnetic interferences

Enclosure
A cabinet for enclosing cable terminations and splices

End Finish
The quality of the end surface of a fiber that is needed for splicing or terminating a connector

Entrance Facility
The part in a building which serves as an entrance for network cables

Epoxy
A thermosetting resin used in fiber optic cable assemblies to secure the fiber with the connector ferrule

Equipment Room
The centralized room that houses telecommunications equipment in a building

ESCON
An IBM standard for connecting peripherals to a computer over fiber optics

Extrinsic Loss
Attenuation caused by an external source extrinsic to an optical transmission system

Fanout
A breakout style multifiber cable designed for ease of connectorization for intra or interbuilding requirements

Ferrule
The alignment tube that is attached to the ends of a fiber optic connector, and are generally made of zirconia, alumina, or plastic

Fiber
A thin filament of glass or plastic that consists of a core and a cladding

Fiber Optics
The use of fiber to guide light transmission for communications or lighting

Fiber Stripper
A tool that is used to remove the buffer coating of a fiber optic cable

Fiber Tracer
An instrument that traces fiber connections and allows for visual checking of continuity

Frequency
The number of cycles per a unit of time, where 1 hertz equals I cycle per second

Fresnel Reflection
Light reflection that occurs from the surface when there is a sudden change in the refractive index as at the end of a fiber

Fusion Splice
A splicing technique that permanently joins the fiber ends by applying heat to fuse or melt the ends together, forming a continuous single fiber

Fusion Splicer
An instrument that performs fusion splice

Gigahertz (GHz)
A unit of frequency that equals one billion cycles per second

Graded Index Fiber
A fiber where the characteristics of the center of the fiber core has the highest refractive index, and decreases towards the cladding

Hertz (Hz)
A unit of frequency that equals one cycle per second

Horizontal Cabling
The portion of cabling that connect the floor distributor to the work area telecommunications outlets 

Index Matching Fluid
A fluid with a refractive index close to glass for reducing reflections caused by refractive-index differences of materials

Index of Refraction
A measure of the speed of light and is a ratio of the speed of light in a material compared to its speed in free space; also referred as the refractive index

Injection Loss
Attenuation caused by the insertion of a component such as a fiber optic connector or splice; also known as insertion loss

Insertion Loss
Attenuation caused by the insertion of a component such as a fiber optic connector or splice; also known as injection loss

Interbuilding Backbone
The backbone cabling between buildings

Intrabuilding Backbone
The backbone cabling within a building

Intrinsic Loss
Attenuation caused within the fiber

Jacket
The outer layer protective coating of a fiber optic cable

Jacket Stripper
A cutter for stripping cable jackets

Jumper
A fiber optic cable that is connectorized at both ends of the cables; also known as a patch cord

Kevlar
A trademark of aramid yarn used inside fiber optic cables for support, protection, and tensile strength

Keying
The mechanical feature of a connector system which guarantees correct orientation of a connection or prevents the connection to a jack or optical fiber adapter of the same type intended for another purpose

Lapping Film
Film that is used to polish the end of the connector ferrules; also referred as polishing paper or polishing film

Laser
An acronym for light amplification by stimulated emission of radiation, which is a device that products high-intensity, directional, monochromatic beam of light

Laser Diode
A laser made of semiconductor materials used to transmit light into optical fibers

Light Emitting Diode (LED)
A semiconductor device that produces light with a wide range of wavelengths in response to an electrical signal

Local Area Network (LAN)
A communications network in small physical areas, such as a building or a group of buildings

Loose Tube Cable
A fiber optic cable design where protective tubes surrounds optical fibers within the outer cable jacket

Loss Budget
A budget of the total losses (attenuation) acceptable in a fiber optic system

Low Smoke Zero Halogen (LSZH)
A cable jacket rating that has features of limited smoke and no halogens when exposed to heat

Macrobend
The bending of a fiber optic cable that could be visually seen by the human eye

Main Cross-connect (MC)
A cross-connect for fist level backbone cables, entrance cables, and equipment cables

Mechanical Splice
The joining of optical fibers via mechanical methods, rather than via fusion splicing

Megahertz (MHz)
A unit of frequency that equals one million cycles per second

Metropolitan Area Network (MAN)
A communications network, larger than a LAN, may consists of several LANs and extend to the size of a metropolitan area

Micro
A prefix for a millionth

Microbend
The small, microscopic bend of a fiber optic cable caused during the manufacturing process

Micrometer (μm)
A unit of distance that equals one millionth of a meter; also referred as a micron

Micron (μm)
A unit of distance that equals one millionth of a meter; also referred as a micrometer

Microscope
A device used to inspect the end surface of a connector

Modal Dispersion
A type of dispersion in multimode fibers where light pulses spread along the length of a fiber

Mode
Light transmission paths in a fiber where the number of modes is determined by the numerical aperture and the core diameter; two broad types are singlemode and multimode

Mode Field Diameter (MFD)
The diameter of one mode of light in singlemode fiber

Monomode Fiber
A type of fiber that transmit light in one single mode, and has a smaller fiber core than multimode fiber; also referred as singlemode fiber

Multi-Fiber Cable
A fiber optic cable that contains more than one fiber

Multimode Fiber (MM)
A type of fiber that transmit lights with more than one mode, and has a bigger fiber core than singlemode fiber

Multiplexing
The transmission of different signals in a single fiber

Nanometer (nm)
A unit of one billionth of a meter

National Electrical Code (NEC)
A US standard for flammability of cable and wiring in buildings

Node
A connection point, either a redistribution point or an end point for data transmissions. In general, a node has programmed or engineered capability to recognize, process, and forward transmissions to other nodes.

Numerical Aperture (NA)
A measure that expresses the light gathering ability of a fiber

Optical Fiber
A thin filament of glass or plastic that consists of a core and a cladding

Optical Fiber Non-conductive Plenum (OFNP)
A cable jacket rating that is non-conductive and used in plenum applications; they have the highest fire retardant rating compared to OFNR and LSZH

Optical Fiber Non-conductive Riser (OFNR)
A cable jacket rating that is suitable for use in riser applications and they are engineered to prevent fire from spreading from floor to floor within buildings

Optical Time Domain Reflectometer (OTDR)
An instrument that measures the transmission characteristics of optical fiber by sending a series of short pulses of light down the fiber and providing a graphic representation of the backscattered light

Outlets
The sockets provided in the work location of a structured cabling system

Overfilled Launch
A condition for launching light into the fiber where the incoming light has a spot size and numerical aperture larger than accepted by the fiber, filling all modes in the fiber

Passive Optical Network (PON)
A point-to-multipoint optical communications network

Patch Cord
A fiber optic cable that is connectorized at both ends of the cables; also known as a jumper

Patch Panel
A hardware that connects backbone cabling to an arrangement of connectors to form cross-connections and interconnections

Physical Contact (PC)
A style of fiber optic ferrule polishing where the fiber is polished to a smooth curve and the adjoining fibers comes into physical contact with no air gaps

Pigtail
A fiber optic cable that is connectorized at one end only

Plenum
The air handling space of a building, such as in raised floors or drop-ceiling tiles

Point-to-Point (P2P)
A direct communications connection between two specific locations

Polarization
The alignment of the perpendicular electrical and magnetic fields that make up a lightwave

Polyethylene (PE)
A plastic material found in the jackets of outside plant fiber optic cables

Polyvinyl-Chloride (PVC)
A plastic material found in the jackets of flame retardant fiber optic cables, ideally deployed in indoor applications

Polyvinyldifluoride (PVDF)
A material found in the jacket of optical fiber non-conductive plenum (OFNP) cables

Preform
A large diameter glass rod where the fiber is constructed

Raceway
Any distribution method designed for holding cables (i.e. conduit, metal or plastic trunking, cable trays, etc.)

Rayleigh Scatter
The scattering of light by particles smaller than the wavelength of the light

Refractive Index
A measure of the speed of light and is a ratio of the speed of light in a material compared to its speed in free space; also referred as the index of refraction

Repeater
A device used to regenerate an optical signal to prevent attenuation and used in long-distance fiber optic links

Return Loss
Light that is reflected and travels back to the origin source; also known as backreflection

Riser
The cable paths between floors in a building

Scattering
A glass property that causes light to deflect from the fiber and contribute to intrinsic attenuation

Server
A computer in a network that provides different services to client computers in the same network

Simplex cable
A type of cable construction that consists of a single fiber core

Signal to Noise Ratio
The ratio of signal level to background noise, measured in decibels

Singlemode Fiber (SM)
A type of fiber that transmit light in one single mode, and has a smaller fiber core than multimode fiber; also referred as monomode fiber

Splice
A method of joining two optical fiber ends

Splice Closure
A closure container used to hold and protect splice trays

Splice Trays
A hardware container used to manage, hold and protect spliced fibers

Split Sleeve
A mechanical fixture contained in an adapter that aligns and holds the terminated fiber connectors; also known as an adapter sleeve

Splitter
A device that takes signal from one fiber and splits it into several other fibers

Step Index Fiber
A fiber with a refractive index that changes abruptly between the core and the cladding

Strength Member
Part of a fiber optic cable that provides extra protection and tensile strength, and may consist of steel strands and aramid yarn

Storage Area Network (SAN)
A high speed network or subnetwork of shared storage devices

Telecommunications Closet
A closet for housing telecommunications equipment, cables and cross-connects

Termination
The preparation of an end of a fiber and connector assembling; also referred as connectorization

Tight Buffered Cable
A type of fiber optic cable where each fiber is tightly buffered by a 880-micron coating for easy handling and connectorization

Topology
The layout of a communications network

Total Internal Reflection (TIR)
Reflection of light as it travels and approaches materials of different refractive indices at an angle greater than the critical angle

Transmitter
A device that acts as both a receiver and transceiver

Trunk cable
Any fiber optic cable that is capable of supporting multiple users or devices from one point to another

Tunable Laser
A laser that can change its frequency over a given range

Waveguide Dispersion
Dispersion caused by light travelling at different speeds in singlemode fibers

Wavelength
The distance an electromagnetic wave travels during the time it takes to oscillate through one complete cycle, and measured in nanometers (nm)

Wide Area Network (WAN)
A large communications network similar to a smaller local area network (LAN)

Zero-Dispersion Wavelength
Wavelength with minimum chromatic dispersion of a singlemode optical fiber