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Fiber Optic Center Glossary

View: Glossary, Acronyms, Military Specifications for Connectors

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There are currently 145 names in this directory beginning with the letter L.
The “long” DWDM transmission band, occupying the 1565 nm to 1625 nm wavelength range.

Label stock
Pressure sensitive materials, which are usually printed, frequently die-cut, furnished in roll or sheet form with a liner, and intended for use as labels.

Lacing and Harnessing
A method of grouping wires by securing them in bundles of designated patterns.

Lacing Cord or Twine
Used for tying cable forms, hook-up wires, cable ends, cable bundles and wire harness assemblies.

In cable manufacture to designate the liquid resin or compound applied to a fibrous braid to prevent fraying, wicking, moisture absorption, etc., in the braid.

Lacquer Finish
A finish applied over braided wire or cable for protection against fraying, wicking, moisture, absorption, abrasion, etc.

Ladder chain
a chain that comprises constitutional units always joined to each other through four atoms, two on each constitutional unit. (IUPAC)

Laminated Flat Cable
Flat cable consisting of insulated conductors lying parallel, adjacent conductors joined by a web. Application in electronics, telecommunications, computers, etc.

Laminated Tape
A tape consisting of two or more layers of different materials bonded together (i.e. aluminum/Mylar®) .

1 ) The process of preparing a laminate. 2) any layer in a laminate. (Compare laminate and wood laminate.)

Lamp Cord
Flexible stranded paralleled 2-conductor cord, rubber or plastic insulated. Used for speaker cord, fans, lamps, etc., where not subject to hard usage.

LAN (Local Area Network)
A network spanning a limited geographical area, providing data communications between computers and peripherals and switching equipment.

The metal portion of a printed circuit board where the pads on a surface mount component are mated. Also called a footprint or a pad.

Used particularly in connection with the transportation of trailers. One lanemetre is one metre of deck, with a width of 2.5 to 3.0 metres. The capacity of ships built for the transportation of new automobiles is normally expressed by the number of cars carried, or by the area of deckspace, in square metres.

Lang Lay Rope
Wire rope in which the wires in the strands in the rope are laid in the same direction

A device attached to certain connectors that permit uncoupling and separation of connector halves by a pull on a wire of cable.

Lanyard Release
A plug connector which may be separated from a counterpart receptacle by axial pull of an attached lanyard. (MIL-STD)

Lap Joint
A joint made by placing one adherend partly over another and bonding together the overlapped portions.

Lap Shear
Test to measure resistance to shear stress by bonding the ends of flat bars in an overlapping position.

Lapping film
Sheets of a thin plastic film with grit of varying coarseness (in microns) that are used to polish fiber endfaces.

Large core fiber
An optical fiber with a comparatively large core, usually a step-index type. There is no standard definition of “large,” but they are generally considered as fibers with diameters of 400 microns or more.

Laser (Fiber Optics)
Light Amplification by Stimulated Emission of Radiation, a device that generates intensified light, usually very directional and over a narrow range of wavelengths. Often a source of light in fiber optic systems.

Laser chirp
Noise created by reflected or crosstalk optical energy entering the lasing chamber.

Laser Diode
A semiconductor diode that emits light in a narrow spectrum; typically over 90% of the light output power concentrated within one angstrom.

Laser-optimized multimode fiber
The ISO/IEC 11801 standard defines two types: the OM3 50/125 fiber, with an effective modal bandwidth of 2,000 MHzkm at 850 nm, and the OM4 50/125 fiber, with 4,700 MHz-km bandwidth.

Attaching a cable to a supporting strand or cable using a steel or dielectric filament around both cable and messenger.

Last mile
The last mile is the local access network that extends from the CO to the end-user subscriber. Also called the local loop network, it is traditionally copper-based and suffers from the bandwidth limitations of that media.

Delay of a signal in time, which can be caused by transmission, processing, rotation, and propagation delays.

Latent strain
A discoloration in a surface to which tape has been applied, which does not become noticeable until some time after removal, usually after the surface has been exposed to sunlight or heat.

A stable dispersion of polymeric substance in an essentially aqueous medium.

Latex caulks or sealants
A caulking compound or sealant using latex as the base raw material. The most common latex caulks are polyvinyl acetate and vinyl acrylic.

Launch Angle
Angle between the propagation direction of the incident light and the optical axis of an optical waveguide.

Launch cable
A known good fiber optic jumper cable attached to a source and calibrated for output power used used as a reference cable for loss testing. This cable must be made of fiber and connectors of a matching type to the cables to be tested.

The length measured along the axis of a wire or cable required for a single strand (in stranded wire) or conductor (in cable) to make one complete turn about the axis of the conductor or cable.

Lay Direction
The direction of the progressing spiral twist in a cable while looking along the axis of the cable away from the observer. The lay direction can be either “left” or “right”.

Lay Length
A term used in cable manufacturing to denote the distance of advance of one element (conductor) of a group of spirally twisted elements, in one turn measured axially.

A step during the optical fiber manufacturing process in which gases are deposited as a wet “soot” upon a quartz rod by flame hydrolysis, ultimately creating a preform for the glass core and cladding of an optical fiber.

Consecutive turns of a coil lying in a single plane.

The twists in twisted-pair cable. Two single wires are twisted together to form a pair; by varying the length of the twists, or lays, the potential for signal interference between pairs is reduced.

LC Connector
A high density connector for fiber optic applications used in both public and private networks. This high performance connector is available in both singlemode and multimode.

Leaching and Non-Leaching
In a leaching wire the plasticizer will migrate when exposed to heat. A non-leaching wire will retain its plasticizer under extreme temperature conditions and remain flexible after baking.

A wire, with or without terminals, that connects two points in a circuit.

Lead Cured
A cable that is cured or vulcanized in a metallic lead mold.

Lead Dress
The placement or routing of wire and component leads in an electrical circuit.

The cable that provides the path for RF energy between the antenna and the receiver or transmitter.

The undesirable passage of current over the surface of or through an insulator.

Leakage Current
The undesirable flow of current through or over the surface of an insulation.

Least square approximation (LSA)
A technique used by OTDRs to automatically measure splice attenuation.


LED Node
Low-Entry Networking Node

Left Lay
1) Strand - Strand in which the cover wires are laid in a helix having a left-hand pitch; 2) Rope - Rope in which the strands are laid in a helix having a left-hand pitch

The drawing of filaments or strings when adhesive-bonded substrates are separated. (See also stringiness and webbing.)

The distance of a communications link measured by a tester with a TDR. For TIA/EIA 568-B.2, the Permanent Link is limited to 90 meters of horizontal cabling embedded in the walls and ceiling plenum. Length is one of the ANSI/EIA/TIA-568-B.2 required tests for a Category 5e UTP cable limited to a total distance of 100 meters including the Permanent Link of 90 meters + 10 meters allowance of line cords, patch cords and up to two cross-connects in a link. (also see NOMINAL VELOCITY OF PROPAGATION)

A measure of the difference between a quantity or value and an established reference.

Life Cycle
A test performed on a material or configuration to determine the length of time before failure in a controlled, usually accelerated environment.

A situation where a section of tape has pulled away from the surface to which it has been applied.

In the laser and optical communications 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 t

Light (Fiber Optic)
An electromagnetic radiation in the wavelength range including infrared, visible, ultraviolet, and X rays, usually the range visible to the human eye, i.e., the energy that enables vision. Light travels in a vacuum at 300,000 km/sec. (186,281 miles per second).

Light Commercial Building
A building or portion thereof that is intended for use with one to four (1-4) non-residential exchange access lines per tenant.

Light Diffusion
Scattering of light by reflection or transmission. Diffuse reflection results when light strikes an irregular surface such as a frosted window or coated light bulb.

Light Emitting Diode
A semiconductor device that emits incoherent light from a p-n junction (when biased with an electrical current). Commonly called LED.

Light Intensity Ratio
Ratio of input light intensity to the output light intensity.

Light source
The fiber optic transmitter in an optical loss test set (OLTS) that uses one or more LEDs or lasers at specified wavelength.Lasers used in communication systems must be stabilized and operating in continuous wave or modulated at 2 kHz.

Light-emitting diode, LED
A semiconductor device that emits light when stimulated by an electrical current. Used in transmitters for multimode fiber links.

Light-Intensity Ratio
Ratio of input light intensity to the output light intensity.

Lightguide (Fiber Optic)
A fiber or a flexible bundle of fibers used to transmit light.

Lightpack Cable
A cable core design that allows bundles of optical fibers in a cable core without central strength members.

Lightwave Communications
Communications using light to carry the information.

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 nm. However, it has become customary to refer to radiation in the speed regi

Limiting Oxygen Index
Percentage of oxygen necessary to support combustion of a specified material.

Limits of Error
The maximum deviation (in degrees or percent) of a thermocouple or thermocouple extension wire from standard emf temperature to be measured.

The ability of a cable to lay flat or conform to a surface as with microphone cables (also see Flexibility).

The portion of a data circuit external to the data circuit-terminating equipment (DCE) that connects it to an exchange, other DCEs, or connects two exchanges.

Line Balance
The degree to which the conductors of a cable are alike in their electrical characteristics with respect to each other, to other conductors, and to ground .

Line Cord
A cord terminating in a plug at one end used to connect equipment or appliances to a power outlet.

Line Drop
A voltage loss occurring between any two points in a transmission line due to there sonance reactance or leakage of the line.

Line Impedance
Impedance as measured across the terminals of a transmission line; frequently the characteristic impedance of the line.

Line Level
Refers to the output voltage level of a piece of electronic equipment. Usually expressed in decibels (e.g., O dBv).

Line Loss
The total of the various energy losses occurring in a transmission line.

Line Speed
The maximum rate of data transfer for a given line.

Line Voltage
Voltage existing in a cable or circuit.

Polymers made up of one long continuous chain, without any excess

Linear chain
A chain with no branch points intermediate between the boundary units (i.e. the end-groups or other branch points). (IUPAC)

Linear copolymer
A copolymer, the macromolecules of which are linear chains.

Linear polymer
A polymer, the macromolecules of which are linear chains.

A term referring to the termination pinout pairs of cable. (also see CONTINUITY and WIREMAP)

An assembly of telecommunications facilities between two points, not including terminal equipment. The interconnection of two nodes in a network. A link may consist of a data communications circuit or a direct channel (cable) connection. It excludes equipment cables and work area cables. An optical cable with connectors attached to a transmitter and receiver.

Link Budget
Optical loss budget that determines the maximum distance allowable between station. Loss and dispersion factors are included.

Link, fiber optic
A combination of transmitter, receiver and fiber optic cable connecting them capable of transmitting data. May be analog or digital.

A contraction of  “Linus’ Unix”

Equipment included in a list published by an organization, acceptable to the authority having jurisdiction, that maintains periodic inspection of production of listed equipment, and whose listing states either that the equipment or material meets appropri

One piece of glazing (also spelled light), synonym: pane.

Litz wire
Wire made from a number of fine, separately-insulated strands specially braided or woven together for reduced skin effect and hence lower resistance to high frequency currents for lower RF losses. The name is Litzendraht wire, German for bundled wire.

Living copolymerization
A copolymerization which is a living polymerization. (IUPAC)

Living polymerization
A chain polymerization in which the concentration of kinetic-chain carriers, under the appropriate conditions for synthesis, remains constant for a period many times longer than the duration of the synthetic procedure. Often, the absence of chain transfer is implied in the term "living polymerization". (IUPAC)

A device that consumes power from a source and uses that power to perform a function.

Load transfer device
Any device embedded in the concrete on both sides of a pavement joint to prevent relative vertical movement of slab edges.

Local access and transport area (LATA)
The geographic area that is the domain of the local exchange carrier. Bell operating companies are generally precluded from carrying traffic across LATA boundaries; this traffic must be handed off to an interexchange carrier.

Local Area Network (LAN)
A data communications network consisting of host computers or other equipment interconnected to terminal devices, such as personal computers, often via twisted-pair or coaxial cables. LAN's allow users to share information and computer resources. Typically, a network is limited to a single premises.  1)A baseband or broadband interactive bi-directional communication system for video or data use on a common cable medium.  2)A communications system whose dimensions typically are less than five kilometers. Transmissions within a local area network generally are digital, carrying data among units.

Local Exchange Carrier
The local wired phone company. The phone carrier providing local transmission services.Defined as either Independent or regional Bell operating company (RBOC).

Local injection and detection (LID)
A type of core alignment fusion splicer that injects light through a macrobend prior to the splice point and detects the light through a macrobend past the splice point. This allows the splicer to achieve maximum core-to-core alignment.

Local loop
The connection between a customer’s telephone or data equipment and a local exchange company or other telephone service provider.

Local Multipoint Distribution System (LMDS)
A “wireless cable” service operating in the 28-GHz band. LMDS uses low-power transmitters, configured in a cellular-like arrangement to transmit video to receivers in homes and businesses.

Device for positioning terminals, splices or contacts into crimping dies, positioner, or turret heads. See STOP PLATE. (MIL-STD)

Locking Spring
A device either on the contact or in the insert to retain the contact in an insert or body. (MIL-STD). Also called Contact Retainer

Locking Torque
Test designed to measure breakaway and prevailing torque of a threaded piece coated with thread locking adhesive.

Log Periodic Antenna
A broadband antenna where the electrical lengths and element spacings are chosen so the bi-directional radiation pattern, impedance and other antenna properties are repeated for several frequencies. The bandwidth is approximately the ratio of the longest dipole element to the shortest.

Long chain
A chain of high relative molecular mass. (IUPAC)

Long Wavelength
A commonly used term for light in the 1300 and 1550 nm ranges.

Long Wire Antenna
Any conductor length in excess of one-half of a wavelength. In a residential television installation, a horizontal run or unshielded lead-in will act as a long-wire antenna and introduce additional signal on top of the regular antenna signal causing ghosts, echoes, and pixelation.

Long-chain branch
A polymeric offshoot from a branched chain. (IUPAC)

Longitudinal Change (Shrink Tubing)
The change in length of tubing when recovered. Expressed in the percent change from the original length.

Longitudinal Conversion Loss
A ratio expressed in dB, of measured differential voltage relative to the common mode voltage on a conductor pair applied at the same end.

Longitudinal Conversion Transmission Loss
A ratio expressed in dB, of measured differential voltage relative to the common mode voltage on a conductor pair applied at the opposite end.

Longitudinal Shield
A tape shield, flat or corrugated, applied longitudinally with the axis of the core being shielded.

Longitudinal Shrinkage
A term generally applied to shrink products denoting the discrete axial length lost through heating in order to obtain the recovered diameter.

Longitudinal Wrap
Tape applied longitudinally with the axis of the core being covered.

Loop Antenna
An antenna consisting of one or more complete turns of a conductor; usually tuned to resonance by a variable capacitor connected to the terminals of the loop. It measures magnetic-field strengths at frequencies <30 kHz.

Loop Resistance
The total resistance of two conductors measured round trip from one end. Commonly used term in the thermocouple industry.

Loop tack
The initial attraction or grab of an adhesive to a substrate without any external pressure. Measured in pounds per lineal inch (PLI).

Loop Thru
A high impedance parallel connection. Also called Bridging

Loopback, or loop-back
The routing of electronic signals, digital data streams, or flows of items back to their source without intentional processing or modification. This is primarily a means of testing the transmission or transportation infrastructure. Example applications exist. It may be a communication channel with only one communication endpoint. Any message transmitted by such a channel is immediately and only received by that same channel. In telecommunications, loopback devices perform transmission tests of access lines from the serving switching center, which usually does not require the assistance of personnel at the served terminal. Loop around is a method of testing between stations that are not necessarily adjacent, where in two lines are used, with the test being done at one station and the two lines are interconnected at the distant station. A patch cable may also function as loopback, when applied manually or automatically, remotely or locally, facilitating a loop-back test. Where a system (such as a modem) involves round-trip analog-to-digital processing, a distinction is made between analog loopback, where the analog signal is looped back directly, and digital loopback, where the signal is processed in the digital domain before being re-converted to an analog signal and returned to the source.

Wiring method which avoids tee joints by carrying the conductor or cable to and from the point to be supplied.

Loose Buffer (Fiber Optic)
Also called "loose tube," a protective tube loosely surrounding a cabled fiber, often filled with a gel.

Loose Tube
Type of cable design in which coated fibers are encased in buffer tubes offering excellent fiber protection and segregation. Mainly used in outdoor cable types.

Loose tube cable
A type of cable where the internal 250-micron fibers are loose within buffer tubes. Types include stranded, central tube, OPGW, ADSS, and microduct cable. Also known as loose buffer cable.

Loose tube gel filled (LTGF)
A loose tube cable structure with buffer tubes filled with gel to restrict moisture intrusion. Mostly replaced with “dry” techniques, it is still used in areas of extreme low temperatures.

Type of cable design in which coated fibers are encased in buffer tubes offering excellent fiber protection and segregation. Mainly used in outdoor cable types.

Loosely-coupled mode
One example would be a high order mode from a LED coupled into a multimode fiber. Higher order modes limit the bandwidth of optical fibers.

1) Energy dissipated without performing useful work.  2) A decrease in power suffered by a signal as it is transmitted from one point to another (transmission loss).

Loss budget
The amount of power lost in the link. Often used in terms of the maximum amount of loss that can be tolerated by a given link.

Loss Factor
The product of the dissipation and dielectric constant of an insulating material. The loss factor of an insulating material is equal to the product of its dissipation and dielectric constant.

Loss windows
Fiber optic transmission typically occurs at 850, 1300, 1310, 1550, and/or 1625 nm. These “windows” were selected because absorption and scattering losses were lower within them. These wavelengths require light sources and photodetectors that operate efficiently over multimode and single-mode fibers. The newer term “bands” is used to define optical windows that match up with optical amplifiers and their optimum transmission wavelengths. The history of the usage comes from the availability of sources and detectors and their operating characteristics over an optical fiber due to the absorption effects at different wavelengths.

Loss, optical
The amount of optical power lost as light is transmitted through fiber, splices, couplers, etc.

Having poor efficiency.

Lossy Line
A cable having large attenuation per unit of length.

Lot Number
The number that identifies one production run of material.

Low Frequency (LF)
A band of frequencies extending from 30 kHz to 300 kHz in the radio spectrum, designated by the Federal Communications Commission.

Low Loss
A cable that has relatively small power loss over long lengths.

Low Loss Dielectric
An insulating material that has a relatively low dielectric loss, such as polyethylene or Teflon.

Low Noise Cable
Cable configuration specially constructed to eliminate spurious electrical disturbances caused by capacitance changes or self-generated triboelectric noise.

Low Tension
Low voltage, as applied to ignition cable.

Low Voltage
Defined by the National Electrical Code as 600 Volts and less. AEIC, ICEA, and UL generally define cables rated up to 2KV as Low Voltage.

Low-smoke zero halogen (LSZH) cable
The standard cable used in Europe in place of plenum or risercable types. Internationally, LSZH cables are used in place of plenum and riser cable jackets. In North America, LSZH cables are used on ships and in tunnels. Also known as zero halogen cable.

Termination, usually crimped or soldered to the conductor, with provision for screwing on to the terminal. Sometimes referred to as Solder Lug.
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