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Fiber Optic Industry Glossary Terms

Multimode, Single-mode, Laser
Optimized...What Does it All Mean?

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FNT Tools has created this online resource of industry terms and "how to" articles written by FNT instructors to better assist our customers and the telecommunication technician community to provide continued quality service.



10BaseT Transmission standard for electrical transmissions over UTP copper cable at 10Mb per second
100BaseTX Transmission standard for electrical transmissions over UTP copper cable at 100Mb per second
1000BaseTX Transmission standard for electrical transmissions over UTP copper cable at 1000Mb per second
10FX Transmission standard for optical transmissions over fiber optic cable at 10Mb per second
100FX Transmission standard for optical transmissions over fiber optic cable at 100Mb per second.
1000FX Transmission standard for optical transmissions over fiber optic cable at 1000Mb per second.
Absorption In an optical fiber, that portion of attenuation resulting from conversion of optical power into heat.
Acceptance Angle Half the vertex angle of that cone within which optical power may be coupled into bound or leaky modes of a multi-mode fiber.
Administration The part of a Premises Distribution System (PDS) that included Subsystem, the distribution hardware and components for adding or rearranging circuits. These components include cross connects, interconnects and there associated patch cords and plugs.
Aging The irreversible change of material properties after exposure to an environment for an interval of time.
Amplitude The maximum value of a varying wave form.
Amplitude Distortion An unwanted change in signal amplitude, usually caused by non-linear elements in the communications path.
Analog Not digital. A continuously varying waveform such as a sine wave.
Angle of Incidence The angle between an incident ray and the normal to a reflecting or refracting surface.
Angular Misalignment Loss The optical power loss caused by angular deviation from the optimum alignment of source to optical fiber, fiber to fiber, or fiber to detector.
Antireflection Coating A thin, Dielectric or metallic film applied to an optical surface to reduce the reflectance and thereby increase the transmittance.
Attenuation In an optical fiber, the reduction of average optical power; this may result from absorption, scattering and other radiation and is generally expressed in dB.
Attenuation Coefficient The rate of diminution of average optical powers with respect to distance along the fiber; may be expressed as dB/km.
Attenuation-Limited Operation The condition prevailing when the received signal amplitude (rather than distortion) limits performance.
Backbone 1. The major transmission path for a structured network.2. The trunk media of a LAN separated into sections by bridges, gateways, or routers. Structured cabling system terminology for that part of the distribution system, including both wire and fiber cables, which is often called riser or house distribution or interconnects.
Backscattering The scattering of light into a direction generally opposite to the original one.
Bandwidth The width of a communication channel, measured as frequency (in cycles per second, or Hertz). A channels bandwidth is a major factor in determining how much information it can carry.
Beamsplitter A device for dividing an optical beam into two or more separate beams; often a partially reflecting mirror.
Bend Radius 1. (Fiber) The radius of curvature that a fiber can bend without breaking or causing excessive loss. 2. (Cable) the minimum radius a cable can be bent without the possibility of causing structural or electrical damage to the cable.
Bi-directional Transmission Signal Transmission in both directions along an optical fiber or other component.
Binary A signal consisting of two states such as: on or off, high or low level, one or zero or presence or absence of a signal.
Bit Contraction of a binary digit; fundamental unit of information expressed in digital form as the choice between only two states-for example, 0 or 1, high or low, on or off.
Bit Stream A digital signal or series of pulses.
Branching Device A device possessing three or more ports which acts to share light among its ports in predetermined fashion without any modification, manipulation or amplification of the input signal.
Broadband The frequency range used in high speed voice, data, video network.
Buffer A protective coating intimate contact with an optical fiber.
Bus A network topology which functions like a signal line which is shared by a number of nodes.
Bus Network A one-cable LAN, in which all work stations are connected to a single cable. On a bus network, all workstations hear all transmission on one cable. Each workstation then selects those transmissions addressed to it.
Byte A collection of bits operated upon as a unit; most are 8 bits long; most character sets use one byte per character. The capacity of storage devices is frequently given in bytes.
Campus The part of the Premises Distribution System that includes Subsystem the cable, inter-building distribution facilities, protectors and connectors that enable communication among multiple buildings on a premises.
Central Wavelength The wavelength (Customarily in nm) of the longitudinal mode with the maximum power level. Measurement must be made after the system has reached steady state.
Cladding The Low refractive index material surrounding the core of an optical fiber.
Collimation The process in which a divergent or convergent beam of radiation is converted into a beam with the minimum divergence possible for that system.
Connector-Induced Optical Fiber Loss The part of connector insertion loss, expressed in decibels(db), due to impurities or structural changes to the optical fiber caused by termination or handling within the connector.
Core The central region of an optical fiber through which light is transmitted.
Core Non-circularity The percent that the shape of the core’s cross section deviates from a circle. Sometimes referred as to core ovality.
Coupling The transfer of energy between two or more cables or components of a circuit.
Coupling Efficiency The efficiency of a optical power transfer between two optical components.
Coupling Loss The power loss suffered when coupling light from one optical device to another.
Cross-connect The apparatus in a distribution system providing for the termination of the optical fibers and the arrangement and testing of circuits. In a fiber-optic cross-connect, incoming and outgoing fibers terminate in ST connectors that fit onto fiber couplings and single fiber jumpers complete the circuits.
Crosstalk An undesired coupling of optical modulated energy between independent optical paths.
Data Integrity A measure of data communications performance, indicating a sparsity or absence of undetected errors.
Data link Service A service that guarantees transmission between two stations sharing the same physical medium.
Decibel (dB) The standard unit used to express the relative strength of two signals. When referring to a single signal measured at two placed in a transmission system, it expresses either a gain or loss in power between the input and output devices. The decibel can express an actual level only when comparing with some definite reference level that is assumed to be zero dB.
Detector A device that converts optical power to other forms.
Dielectric An insulating (non-conducting) medium.
Digital Discretely variable as opposed to continuously variable. Data character are coded indiscreet, separate pulses or signal levels. Contrasts with Analog.
Distributed Architecture A LAN that uses a shared communications medium; used on a bus or ring LANs; used shared access methods.
Download The process of loading software into the nodes of a network from one node or device over the network media.
DWDM Dense Wavelength Division Multiplexing – More than two wavelengths transmitted at the same time on one fiber, either mono-directional or bi-directional.
EIA (Electronic Industries Association) The U.S. national organization of electronic manufacturers. It is responsible for the development and maintenance of industry standards for the interface between data processing machine and data communications equipment.
Electromagnetic Referring to the combined electric and magnetic fields caused by electron motion through conductors.
EMI (Electromagnetic Interference) External signals that disrupt the data being transmitted on a local area network or electronic device being operated. Typically, these external signals emanate from universal motors with brushes, fluorescent lights, personal computers, printers or other devices including copying machine, etc. The FCC (Federal Communications Group) regulates this area.
Equipment Room The room in which voice or data common equipment are housed, protected and maintained, and circuit administration is performed using the trunk and distribution cross-connects.
Equipment Wiring Subsystem The part of a Premises Distribution System that includes the cable and distribution in an equipment room and that interconnects system-common equipment, other associated equipment and cross-connects.
FDDI (Fiber Distributed Interface) An ANSI defined token passing ring using fiber optic media to attain a 100 mbps transmission rate.
Fiber Optic Cable A cable consisting of one or more optical fibers protected by buffering material, inner cable components ( such as strength members, central member, water blocking gel, rodent-proof armor, sub-unit jacket, etc.) and an outer jacket.
Fiber Optics Transmission of energy by light through glass fiber. A type of technology that uses light as an information carrier. Fiber optic cables (light or wave-guides) are a direct replacement for conventional coaxial cable and wire pairs. The glass-based transmission cable occupies far less physical volume for an equivalent transmission capacity; the fibers are immune to electrical interference.
Fan-out Kit Used to protect your bare fiber and prepare loose-tube cable for direct termination. Fan-out Kit separate 250 µm fibers and route them into color-coded 900 µm buffer tubes.
Frequency Is the number of wave crests that pass an imaginary given point in relation to time. Frequency is usually expressed in cycles per second or Hertz. Fiber transmissions express frequency in fractions of a second such as mega-Hertz and terra-Hertz.
Frequency Deviation A swing away from the nominal frequency.
Frequency Range The frequency spectrum allocated for use by any frequency selective or component.
Frequency Response The variation of gain or attenuation with frequency.
Fusion Splicer: Tool used to splice two optical cables together by means of either a core alignment, cladding alignment or PAS alignment system. A powerful electric spark jumps across a set of electrodes as the cables meet in order to melt glass ends together creating a fusion splice. See Fusion Splice.
Fusion Splice: A permanent joint accomplished by applying localized heat sufficient to fuse or melt the ends of two optical fibers together, forming a continuous single fiber.
Gain The increase in signaling power that can occur during transmission from one point to another and measured decibels (dB).
Gigabit 1000 megabits per second.
Infrared Radiation Radiant energy within the wavelength range 789 to 1000 nanometers; invisible energy given off by heated bodies which transmits heat and will pass through glass.
Input A signal which is applied to a piece of electric apparatus, or the terminals on the apparatus to which a signal or power is applied.
Interference Disturbances of an electrical or electromagnetic nature that introduce undesirable responses into other electronic equipment.
ISDN (Integrated Service Digital Network) An international standard currently under-development, that will cover a wide range of data communication issues but primarily the total integration of voice and data.
LAN (Local Area Network) A user-owned, user operated, high volume data transmission facility connecting a number of communications technology provides a high-bandwidth, low cost medium to which many nodes can be connected.
LC Connector A small form factor (SFF) single fiber, optical fiber used for the termination of both multimode and singlemode optical fiber cables. A two-fiber, duplex connector option is also available. The housing mechanism of the LC connector (simplex and duplex) is a push pull type connection.
LED (Light Emitting Diode) Semiconductor device, much more reliable that an incandescent lamp, used for status display purposes in electronics equipment.
Lightwave The Term used to describe the signal providing communication over optical fiber.
LIU (Lightguide Interconnection Unit) The basic building block of the lightwave cross-connect and the lightwave interconnect. It is a square metal cabinet capable of accepting connector panels, each holding up to six coupling sleeves.
Loop A closed circuit unidirectional signal path connecting input-output devices to the system.
Lumen A unit of measurement for light output.
MAN Metropolitan/Municipalities Area Networks
Megabit 1000 bits per second.
MegaHertz (MHz) 1000 cycles per second.
Multimode Optical fiber which allows more than one mode of light to propagate. A Step-index fiber has a core of uniform refractive index while in a graded-index fiber the refractive index of the core smoothly varies with the radius.
Multiplex The use of a common physical channel in order to make two or more logical channels, either by splitting of the frequency band (frequency-division multiplex), or by utilizing this common channel at different points in time (time-division multiplex).
Mechanical Splice Is a junction of two or more optical fibers that are aligned and held in place by a self-contained assembly. The fibers aren't permanently joined, but are cleaved and precisely held together so that light can pass from one to another.
MT-RJ Connector A small form factor (SFF) single fiber, optical fiber used for the termination of both multimode and singlemode optical fiber cables. The housing mechanism of the MT-RJ connector is a push pull type connection.
Network A series of nodes connected by communication channels.
Noise In a cable or circuit any extraneous sounds or signal which tends to interfere with the sound or signal normally presents in or passing through the system.
Optical Connectors Connectors designed to connect or disconnect either single or multiple optical fibers repeatedly. Optical connectors are used to connect fiber cable to equipment and interconnect cables.
Optical Cross-connect A cross-connect unit used for circuit administration and built from modular cabinets. It provides for the connection of individual optical fibers with optical fiber patch cords.
Optical Fiber A very thin, flexible glass or plastic fiber carrying high bandwidth digital analog signals in the form of pulses of light. Fiber can carry a thousand times mare information than conventional copper wire. Lasers or LEDs emit pulses of light, which are propagated through the fiber by a process of internal reflection. A fiber consists of two layers of glass or plastic enclosed in a protective buffer.
Optical Interconnect An interconnect unit used for circuit administration and built from modular cabinets. It provides interconnection for individual optical fibers but, unlike the optical cross-connect panel, it does not use patch cords. The optical interconnect provides some capability for routing and re-routing circuits, but is usually used where circuit rearrangements are infrequent.
Optical Loss Testing Is used to measure loss and power levels, locate faults and polarity issues, and inspect connector endfaces within communication networks.
Optical Splice A fiber optic splice provides the means by which two or twenty-four fiber optic cable ends are permanently joined together. Two types of optical splices are supported by PDS. An array splice, which joins twenty-four optical ends, and a rotary mechanical splice, which joins two optical fiber ends.
Optical Transceiver An optical device which both transmits and receives data over optical fiber.
OTDR (Optical Time Domain Reflectometer) An instrument that located faults in optical fibers or infers attenuation from back scattered light measurements.
Output The useful power or signal delivered by a circuit or device.
PAS Alignment (Profile Alignment System) is a core to core alignment system on the both X and Y axis used in fusion splicing.
PCM (Pulse Code Modulation) A modulation technique use to convert analog voice signals into digital form.
Refraction and Reflection Reflection is simply lightwaves that are unable to penetrate a medium. Refraction on the other hand is caused when lightwaves penetrate materials of different refractive indexes and are deflected or bent at various angles within a medium.
Ribbon Fiber Cable A cable that accommodates 1 to 12 ribbons, each ribbon having 12 fibers for a cable size range of 12 to 144 fibers. Ribbon cables are designed for use in large distribution systems where small cable size and high pulling strength are important.
Signal-to-Noise Ratio A ratio of the amplitude of a desired signal to the amplitude of noise, usually expressed in dB.
Single Mode Optical Fiber in which only one mode of light can propagate.
SC Connector Square Body connector fashioned from push/pull design development by 3M.
ST Connector A metal connector with a "straight tip” (ST) to join the ends of optical fibers so their fine light conducting cores meet exactly, ensuring precise optical alignment. Each end carries the same type of single element plug and cylindrical sleeve. These attach to either side of a common housing, called a lightwave coupling, that holds the cables together. ST is a registered trademark of AT&T but various manufacturers make several versions of the ST type of connector.
Structured Cabling System The transmission network inside a building or group of buildings that connects various types of voice and data communication devices, switching equipment and other information management systems together, as well as to outside communication networks. It includes the cables and distribution hardware components and facilities between the point where building wiring connects to the outside network lines back to the voice and data terminals in an office or other work locations.
Termination Kit A combination of tools or devices, used to strip, prep, terminate, crimp, polish and inspect cable elements.
TIA (Telecommunications Industries Association)
TDM Time Division Multiplexing A method utilizing channel capacity efficiently in which each node is allotted a small time interval, in turns, during which it may transmit a message or a portion of a message(for instance, a data packet). Nodes are given unique time slots during which they have exclusive command of the channel. The messages of many nodes are inter-weaved for transmission and then demultiplexed into their proper order at the receiving end.
Wavelength s defined as the distance from one wave crest or trough to the next.
WAN (Wide Area Network) A network that uses common carrier-provided lines, such as, ATT or MCI fiber optic cable systems.
WDM (Wavelength Division Multiplexing) Two wavelengths transmitted on a single fiber at the same time. There is a greater wavelength separation on WDM than on DWDM.