Glossary – A


Glossary start with Letter A:

Abrasion resistance
The surface ware resistance of the fiber optic cable.

Caused by impurities introduced during the manufacturing process, absorption creates loss in a fiber by turning light energy into heat. The amount of absorption is determined by the wavelength and depends upon the composition of the glass or plastic. Absorption and scattering are the two causes  of intrinsic attenuation in an optical fiber.

Acceptance angle
See Critical angle. The minimum angle at which light can be propagated within a fiber. Sine critical angle equals the ratio of the numerical  aperture to the index of refraction of the fiber core.

Acceptance test
A test to confirm that an optical cable or fiber link meets the original established performance specifications.

Active device
Compare with Passive Device, An active device is a device that requires electrical power. One type is those that convert signals between electrical and optical (E – O – E) formats such as lasers, LEDs, and photo diodes. Active devices also can manipulate light, such as optical amplifiers and modulators.

Active optical cable (AOC)
A fiber optic cable that has been pre-terminated with an external electrical end-face, thereby removing the termination process. The electrical end-faces can be manufactured with most module formats. The most common module formats are the SFP and HDMI interfaces, but DVI, VGA, SFP+, and QSFP+ interfaces also can be provided.

A Mechanical device used for fiber core connection after termination, it is also a mechanical device that transitions the transmitter or receiver of an optical loss test set (OLTS) to the fiber optic cable assembly.

Add/drop multiplexer (ADM)
A mid-span electronic element that provides optoelectric/ electro-optic conversion to add, drop, or multiplex photonic signals.

Aeolian vibration
Wind-induced vibration, usually high frequency, which causes oscillation of cable.

A type of installation in which the cable is connected to poles or towers by means of clamps or other attachment hardware.

Aerial cables
Cables that are designed to handle environmental concerns such as wind and ice loading, pollution, UV radiation, thermal cycling, stress, and aging in aerial placements. There are several variations of aerial cables including Figure-8, OPGW and ADSS.

Air blown fiber (ABF)
An installation technique developed by British Telecom where micro ducts or “pipe cables” are installed, and then optical fibers or fiber bundles are blown into the cable with spans reaching 10,000 feet.

Air handling plenum
A space within a building that is designed for the movement of environmental air, e.g., a space above a suspended ceiling or below an access floor.

Air polish
The first polish of a ferrule or termini after the fiber has been cleaved. The lapping film is passed over the connector endface in the air to polish the fiber stub just above the ferrule endface.

Alignment sleeve
An appliance for mating and holding two connector ferrules in alignment. Also known as a C-clip.

First two letters of ADSS Cable, means no metal elements.

All-dielectric self-supporting (ADSS)
A loose tube cable structure without any metallic elements. Specified by the IEEE P-1222 standard, ADSS cable is designed for long spans with tension levels up to 10,000 feet (about 3km). Six variations are listed, based on the cable’s outside diameter.

All-optical network (AON)
A network that uses only optical components to produce, direct, condition, control, and connect optical signals.

American National Standards Institute (ANSI)
The official American standards body through which standards are published and various other standards committees are accredited.

Amplified spontaneous emission (ASE)
The ratio of the optical power at the center of the laser line width to the optical power at a given distance, as measured using an optical spectrum analyzer with a set resolution bandwidth.

Amplitude modulation (AM)
An analog transmission method, used by the CATV industry, in which information carried by an electronic signal causes the height of the sine wave (amplitude) to vary. Principle forms include QDM, QAM, SSB, and VSB.

In adhesives, a bonding method that uses its own chemical reaction to complete the adhesion.

A data format using continuous physical variables such as voltage amplitude (AM) or frequency (FM) variations that are analogous to the original signal.

Angled physical contact (APC)
A ferrule endface at 8° that minimizes Fresnel reflections when in contact with another APC termination. APC polishes normally have a component reflectance value of 60-70 dB. They are most often used in analog, DWDM, and FTTx installations.

Angular misalignment
The fiber optic cores of a mated pair of connectors are held at an angle, either by mispolish, worn alignment sleeve, or contamination.

Apex offset
As measured by an interferometer, when the radius of curvature of a connector’s endface polish is distorted enough to cause the fiber optic to appear off center.

Application-specific optical fiber (ASOF)
Fibers built for specific applications such as those doped with erbium for use in fiber amplifiers or the high numerical aperture fibers used for manufacturing filters and gratings.

Aramid yarn
A woven strength member incorporated into fiber optic cable assemblies to provide protection and mechanical bonding. Usually consists of Kevlar™.

The discharge from the electrodes of a fusion splicer.

In networks, it is how the components are connected to and operate with one another. The term “network architecture” focuses on how fiber optic system elements communicate including functional organization (services) and configuration (topology and communications). Network architectures are usually designed as to their protocols. B-PON, G-PON, EPON, GEPON, WDM-PON, CATV, Cable Modem, SONET, ATM, Ethernet, etc., are examples of network architectures.

Armored cable
Cable with metallic sheathing or rods placed under or between cable jackets to prevent rodents from damaging the internal
cable elements.

Array connector
Typically, connectors with multiple fibers in a small form factor housing, i.e., MPO, MTP, MT-RJ.

Arrayed waveguide grating (AWG)
A device that allows multiple wavelengths to be combined and separated in a DWDM system.

Drawings that provide accurate depictions of cable running lines, pedestal locations, electronic sites, manholes, marker posts, etc., to aid with the management of cable assets and allow the facilities to be located, protected, maintained, and modified.

Asymmetric digital subscriber line (ADSL)
A high-speed transmission technology that uses existing copper wires and involved electronic equipment to send digital signals from the telephone company central office to the subscriber’s premises. It sends more information one way than the other, hence it is “asymmetric.”

Asynchronous transfer mode (ATM)
A high-speed call-based transmission scheme that provides bandwidth on demand for multimedia (voice, video, or data).

Asynchronous transmission
A transmission method with no clocking signal in which each character of information is individually synchronized through start and stop elements that notify the receiver of incoming data without regard for timing of the previous character. (Compare with “synchronous transmission.”)

The loss of optical power, whether caused intrinsically (absorption, scattering, microbends, etc.), or extrinsically by components (connectors, splices, splitters, etc). Expressed as dB or dB/km (with fiber).

A component that incorporates a specific amount of loss into an operational optical network. Attenuators also provide a safety margin in planned networks to allow for electronics degradation over time, or physical changes to the optical component portion of the network. Attenuators come in two styles, fixed and variable. Variable optical attenuators are used for testing systems for dynamic range and quality of signal testing.

Automatic protection switching (APS)
Utilizing optical monitoring equipment, a network can be automatically switched over to a secondary network when the original network experiences a higher than normal loss or becomes inoperable.

Automatic test equipment (ATE)
Test equipment that is computer programmed to perform measurements on a device without changing the test setup.

Avalanche photodiode (APD)
A photodiode that takes advantage of avalanche multiplication of photocurrent to convert one photon to multiple electrons.

Average power
The average over time of a modulated signal.

Axial ray
A ray passing through the axis of the optical waveguide without any internal reflection.