Fiber Optic Glossary



850 VCSEL:
850 nm Vertical Cavity Side-Emitting Laser, a type of light source that is commonly used in Gigabit Ethernet applications.


A form of attenuation in fiber optic cables, in which part of the light signal being sent through an optical fiber is absorbed by impurities found in that fiber’s glass. Between 3 and 5 percent of fiber optic signal loss is due to absorption.


A method for testing signal loss in fiber optic cables.


Bend Loss:
A form of attenuation that can result from an optical fiber being curved around a restrictive radius, or from micro bends imposed on a fiber by external forces.


Bend Radius:
The measurement of how much a fiber optic or metallic cable can bend without any adverse effects.


(fiber optic) a soft material, which physically isolates and individual fibers in an optical fiber cable or bundle and protects them from small geometric irregularities, distortions, and the roughness of adjacent surfaces.


A device used to line an opening, which prevents abrasion to any wires and cables that are being passed through that opening.


CDRH Laser Class Class 1:
If at all possible, it is best to keep a product in the lowest-power classification, Class I. This will minimize performance, labeling and user informational requirements.


Center Wavelengths: Center Wavelength (Laser)
1. The nominal value central operating wavelength defined by a peak mode measurement where the effective optical power resides.
2. The wavelength of an optical source that might be considered its middle. One measure of this is the average of the two wavelengths corresponding to the Full Width Half Maximum-FWHM.


Central Member:
A strengthening element, which is run down the center of a cable to provide it with extra support.


In fiber optic cables, cladding serves as a sheath over the core, providing optical insulation and protection for the reflection interface.


Coherent Source:
A light source, which emits a very narrow, unidirectional, monochromatic beam of light into optical fiber.


Coupling Loss:
Signal losses in fiber optics, due to small differences in the numerical aperture, core diameter, core concentricity and tolerances of splicing connectors, when two fibers are aligned. Also known as Splicing Loss and Transfer Loss.


Undesired electrical currents in conductors, which are caused by electromagnetic or electrostatic coupling from other conductors or external sources; also, leakage of optical power from one optical conductor to another.


An aggressive solvent or solution used to remove heavy oils or grease


A device that picks up light from an optical fiber and converts the information into an electrical signal.


A variation of refractive index within an optical fiber, causing light of different wavelengths to travel through the fiber at different velocities.


Relative units or decibel


Absolute units. dBm is similar to dB, or decibel, except that where dB is relative to the power of the input signal, dBm always relates to a 1 milliwatt signal.


The intentional addition of select impurities to glass, done by the manufacturer in order to achieve certain refractive properties in optical fiber.


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When a standard appears in the Official Journal (OJ), it has been harmonized (approved) by the European Committee for Electrotechnical Standardization (CENELEC) and given a number beginning with an EN prefix. The EN stands for European Norm, which indicates all member countries of the EU recognize this standard and will honor it as the norm throughout the European Union. Product and generic standards are two common EMC standards that appear in the OJ.

Product standards describe a product or product-family classification. Generic standards are categorized by the environment that the product will be marketed in: domestic or heavy industrial. If there is no product standard for your device, you are not considered exempt but rather would use generic standards by default.


Safety regulations for electrical measuring instruments, control instruments and laboratory equipment

Domestic Environment

EN50081-1: 1992 Generic Emission Standard—seldom used today.


EN50082-1: 1992 Generic Immunity Standard—often used today.


Heavy Industrial Environment

EN50081-2: 1994 Generic Emission Standard—seldom used today.


EN50082-2: 1995 Generic Immunity Standard—often used today.


EN55011, Group 1, class A – deals with emissions


IEC 801-x:
Electromagnetic Compatibility for Industrial-Process Measurement and Control Equipment. This series of standards has been superseded by the IEC 61000-4-x series, which is referenced in more recent product family and generic EMC standards.


IEC 801-1, General Introduction, 1984.

IEC 801-2 , Electrostatic Discharge Requirements, 1991.

IEC 801-3 , Radiated Electromagnetic Field Requirements, 1984.

IEC 801-4 , Electrical Fast Transient/Burst Requirements, 1988.


Exit Angle:
The angle between the output radiation vectors and the axis of the fiber or fiber bundle.


FC Connector:
A type of fiber optic connector, which provides a strong connection by way of its threaded plug and socket.


Fabry-Perot Laser:
A type of diode laser (also known as a semiconductor laser) that is made up of two reflective surfaces separated by an amplifying medium. Named after Charles Fabry and Alfred Perot, the French physicists who developed it.


A thread or strand of glass used to transmit optical (light wave) information.


Fiber Dispersion:
Light pulse spread in a fiber, caused by the differing transit times of various modes.


Fiber Multiplexing:
A multi-channel data transmission method, in which each channel is assigned to a specific optical fiber.


Fiber Optics:
A light-wave or optical communications system in which electrical information is converted to light energy and transmitted to another location through optical fibers, where it is then converted back into electrical information.

Fiber Optic Cable:
In fiber optics, a jacketed fiber or jacketed bundle in a form that can be terminated. Fiber optics (optical fibers) are long, thin strands of very pure glass about the diameter of human hair. They are arranged in bundles called fiber optic cables and used to transmit light signals over long distances.


Fiber Tubing:
A loose, crush-resistant cylinder applied over individual fibers to provide mechanical protection.


A nonconductive material that is used to enhance the shape, flexibility, or tensile strength of a cable.


A material, device or assembly of parts installed in a cable system in a fire-rated wall or floor to prevent the passage of flame, smoke or gasses through the rated barrier.


FOCIS: The acronym for Fiber Optic Cable Intermateability Standard, which is a set of TIA specifications for the interconnection of fiber optic plugs and sockets.


A type of optical fiber in which the refractive index of the core is in the form of a parabolic curve, decreasing toward the cladding. This type of fiber provides high bandwidth capabilities.


Hydroflouroether (cleaning solvent)


A cabling industry nickname for loose-tube, gel-filled, outdoor-use fiber optic cable.


Incoherent Source:
A light source that emits wide, diffuse beams of light in many wavelengths.


Index-Matching Fluid:
Fluid with a refractive index the same as the fiber core; used to fill air gaps between fiber ends at connectors.


Indoor Plant Cables:
Cables rated for use in stable indoor environments. Indoor Plant Cables are typically designed for easy termination, and must meet National Electrical Code and local building requirements.


Acronym for Integrated Services Digital Network, a type of digital network in which voice, data and images are switched and transmitted through a single port.


Insertion loss measurements:
The insertion loss characterize the sensitivity of a transducer.In order to measure the insertion loss, an ultrasonic burst is emitted by a transducer. The same transducer receives an echo issued from a plane perpendicular target, which acoustic impedance differs very much from the liquid used as a transmitting media.


In fiber optics, a covering over a fiber, bundle of fibers or cable, which provides protection against the environment.


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The mechanical feature of a connector system, which guarantees correct orientation of a connection, and also prevents connection to jacks or optical fiber adapters that are of the same type, but intended for different purposes.


Laser Diode:
A semiconductor diode which, when pulsed, emits coherent light.


Launch Angle:
The angle between the radiation vector and axis of a fiber or fiber bundle.


LC Connector:
An identical, half-sized version of push-pull style SC optical connectors.

Acronym for Light Emitting Diode, a device used to send light signals through multimode fiber, which is capable of transmitting at speeds of up to 622 Mb/sec.


Local Light Injection and Detection System
, an alignment method used on fibers being spliced or connected, in which optical power transmitters and detectors are used to ensure that light is being effectively transmitted from one fiber to the next.


Light-Intensity Ratio:
The ratio of input light intensity to output light intensity.


Light Guide:
A flexible bundle of fibers, used to transmit light.


Light Source:
An object capable of emitting light. In fiber optics, the light source is normally an LED or a laser.


Light Wave Communications:
Communications in which light is used for the transmission of information.


Linearity is the behavior of a circuit, particularly an amplifier, in which the output signal strength varies in direct proportion to the input signal strength. In a linear device, the output-to-input signal amplitude ratio is always the same, no matter what the strength of the input signal (as long it is not too strong). In an amplifier that exhibits linearity, the output-versus-input signal amplitude graph appears as a straight line. Two examples are shown below. The gain, or amplification factor, determines the slope of the line. The steeper the slope, the greater the gain. The amplifier depicted by the red line has more gain than the one depicted by the blue line. Both amplifiers are linear within the input-signal strength range shown, because both lines in the graph are straight.


An acronym for Low Smoke Zero Halogen, which can also be abbreviated as LS0H. This safety classification applies to thermoplastics such as polypropylene, which give off little smoke and no halogens when burned.


A large, visible bend in fiber optic cabling, which affects the refractive index of the area in which it occurs. Macrobending generally doesn’t cause irreversible damage to optical fiber, and any attenuation caused by it can usually be fixed by correcting the bend.


Material Scattering Loss:
Loss due to fluctuations in the refractive index and inconsistencies in material composition and temperature.


Max. spectral width:
In telecommunications, spectral width is the wavelength interval over which the magnitude of all spectral components is equal to or greater than a specified fraction of the magnitude of the component having the maximum value.
In optical communications applications, the usual method of specifying spectral width is the full width at half maximum. This method may be difficult to apply when the spectrum has a complex shape. Another method of specifying spectral width is a special case of root-mean-square deviation where the independent variable is wavelength, λ, and f (λ) is a suitable radiometric quantity.


Micro-bending Loss:
Loss due to small irregularities along the core- clad interface of the fiber.


Modulated Output:
Not continuous.


Modulation frequency:
In telecommunications, frequency modulation (FM) conveys information over a carrier wave by varying its frequency (contrast this with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant). In analog applications, the instantaneous frequency of the carrier is directly proportional to the instantaneous value of the input signal. Digital data can be sent by shifting the carrier's frequency among a set of discrete values, a technique known as frequency-shift keying.

Multimode fiber optic cable has a large-diameter core that is much larger than the wavelength of light transmitted, and therefore has multiple pathways of light-several wavelengths of light are used in the fiber core.
Multimode fiber optic cable can be used for most general fiber applications. Use multimode fiber for bringing fiber to the desktop, for adding segments to your existing network, or in smaller applications such as alarm systems. Multimode cable comes with two different core sizes: 50 micron or 62.5 micron..


Multimode Optical Fiber:
An optical fiber that will allow several modes to propagate. The fiber may be classified as either graded-index or step-index . See also: Optical Fiber Cable.


NEC Article 770:
A National Electrical Code standard for indoor-use fiber optic cable, which states that indoor-plant optical fiber cable must be flame and smoke resistant, in accordance with its specific building application.


nm wavelengths:
Wavelengths are measured in Nanometers.

A nanometer is a unit of spatial measurement that is 10-9 meter, or one billionth of a meter. It is commonly used in nanotechnology, the building of extremely small machines


"Optical fiber conductive general purpose" cables that meet the same flame propagation requirements of general use raceways (FT-1).

"Optical fiber conductive plenum" cables that meet the same flame propagation and smoke density requirement of plenum raceways (FT-6).

"Optical fiber conductive riser" cables that meet the same flame propagation requirements of riser raceways (FT-4).

"Optical fiber nonconductive general purpose" cables that meet the same flame propagation requirements of general use raceways (FT-1).

"Optical fiber nonconductive plenum" cables that meet the same flame propagation and smoke density requirements of plenum raceways (FT-6).

"Optical fiber nonconductive riser" cables that meet the same flame propagation requirements of riser raceways (FT-4).


Not permitting the passage of light.


Optical Communication Cable:
Fiber with a protective jacket around it.


Optical Conductors:
Materials that are capable of transmitting light energy.

Optical Fiber Cable:
A cable consisting of one or more optical fibers which transmits modulated light for the purpose of control, signaling or communications.


Optical Fiber Duplex Adapter:
A mechanical media termination device, designed to align and join two duplex connectors.


Optical Fiber Duplex Connector:
A mechanical media termination device designed to transfer optical power between two pairs of optical fibers.


Optical Power Meter :
An optical power meter (or laser power meter) is a device for the measurement of the power in a laser beam. Most power meters are based on the principle that the optical power is converted to heating power in some absorber structure, and the resulting temperature rise (or some temperature difference) is measured, e.g. with a thermopile. Such thermal power meters are useful for average powers between ≈0.01 W and several kilowatts; typically, some water cooling is required for powers above roughly 10 W. They are rather robust (although too tight focusing onto the absorber should be avoided), moderately precise, usable in a wide wavelength range (with rather wavelength-independent sensitivity), and relatively slow


Optical Wave guide:
A fiber that is used for optical communication, in the same way that a waveguide is used for microwave communications.


Outside Plant Cables
, for use outdoors and in less-stable environments. Cables that fall into this category must have excellent resistance to disruptive mechanical forces, attenuation, and environmental extremes involving water, heat and ultraviolet rays.


Packing Fraction:
The ratio of active, cross-sectional areas of fiber core to the total number of end surfaces in a fiber, or fiber bundle.


The buffing of fiber ends to an optically smooth finish, generally using an abrasive.


A measure of the reflected signal relative to the signal incident upon the component. Reflectance is expressed as a negative value. A value of -55 dB means the reflected signal is 55 dB LESS than the transmitted signal. The smaller (more negative) the reflectance value, the better the performance. For example, a reflectance of -65 dB is better than a value of -55 dB.


A light wave or ray’s change in direction.


The bending of light waves or rays as they move from one material to another, due to a difference in optical density between the two materials.


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SC Connector:
A type of fiber optic connector that latches by way of a push-pull mechanism.


Singlemode fiber optic cable has a small core and only one pathway of light. With only a single wavelength of light passing through its core, singlemode realigns the light toward the center of the core instead of simply bouncing it off the edge of the core as with multimode. Singlemode is typically used in long-haul network connections spread out over extended areas--longer than a few miles. For example, telcos use it for connections between switching offices. Singlemode cable features a 9-micron glass core. 


Single Mode Fiber:
A fiber waveguide in which only one mode will propagate. This type of fiber, which is usually used with laser diodes, has a very small core diameter (approximately 8mm) that allows for signal transmission at extremely high bandwidths.


Skew Rays:
A ray of light that enters a fiber core at a very high angle, and does not intersect the fiber axis.


Source Coupling Loss:
A decrease in light intensity, which occurs when light from source passes into fiber.


Spectral Bandwidth:
A difference between wavelengths, in which an illumination’s radiant intensity is equal to one-half of its peak intensity.


Spectral Response:
The response of a detector – or system – over different wavelengths.


Frequencies that exist in a continuous range and have a common characteristic.


Speed of Light (c):
2.998 x 10 8 meters per second.


ST Connector:
A standard type of fiber optic cable connector that employs a half-twist, bayonet-style plug and socket.


Step Index Fiber:
A multimode fiber consisting of a core of uniform refractive index, which is surrounded by cladding of slightly lower refractive index.


Tension Member:
A member included in a fiber cable to add tensile strength.


Transmission Media:
The various types of wire and optical fiber cable used for transmitting voice or data signals. Typically, wire cable includes twisted pair, coaxial and twin-axial. Optical fiber cable includes single, dual, quad, stranded and ribbon.


The transmission of light rays in a way that allows objects to be seen through a material.


TF Solvent:
Used as a solvent and refrigerant; It is used in fire extinguishers and as a blowing agent. It has a wide range of cleaning applications and vapor degreasing.


Vertical Cavity Surface Emitting Laser. This is a laser with high-speed capability and concentrated light, which is used for supporting 1 gigabit and 10 gigabit Ethernet transmission over multimode fiber.

Vapor Degreaser:
A components cleaning process used to remove heavy grease and soil from communications or electronics systems as well as aircraft components and medical equipment


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