General Cable Fiber Optics Catalog
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Fiber Optic Technical Information Glossary Absorption: Physical phenomenon that attenuates light traveling in fibers by converting it into heat, thereby raising the fiber's temperature. Absorption results from impurities and defects in the glass structure. Acceptance Angle: The half-angle of the cone within which all incident light is totally internally reflected by the fiber core. For graded index fibers, acceptance angle is a function of position on the entrance face of the core. Adapter: A mechanical media termination device designed to align and join fiber optic connectors. Often referred to as a coupling, bulkhead, or interconnect sleeve. Amplitude: Height of a waveform that represents signal strength. Analog: A format that uses continuous physical variables such as voltage amplitude or frequency variations to transmit information. Angle of Incidence: The angle between an incident ray and the normal to a reflecting surface. Angle of Refraction: Angle formed between a refracted ray and the normal to the surface. This angle lies in a common plane with the angle of incidence. Aramid Yarn: Strength elements that provide tensile strength, support and additional protection of fiber bundles. It is commonly referred to as Kevlar (a DuPont trademark). Armor: Protective covering, usually metal, used underneath plastic jackets to provide additional environmental protection in harsh environments. Attenuation: Loss of signal strength between points. Usually measured in decibels per a unit length (e.g., dB/km). Backbone: The main portion of network cabling connecting equipment rooms or communications closets. These cables often have the largest number of fibers and/or the longest continuous cable runs. Backscattering: The scattering of light in a direction opposite to the original one. Coating: Material put on a fiber during the drawing process for mechanical protection. Bandwidth: A characterization of the information-carrying capacity of a multimode optical fiber. It is expressed in terms of frequency and is often normalized to a unit length (e.g., MHz-km). Conduit: Pipe or tubing through which cables can be pulled and housed. Bend Loss: A form of increased attenuation in a fiber that results from bending a fiber around a restrictive curvature (a macrobend) or from minute distortions in the fiber (microbends). Bend Radius: Radius of curvature that a fiber can bend without breaking. Breakout: Multifiber cable constructed in the tight buffered design with individually jacketed fibers. Designed for ease of connectorization and rugged applications for intra- or interbuilding requirements. Buffer: Coating used to protect optical fiber from physical damage. Types include tight buffer (indoor) or loose tube (outdoor). Bundle: Several individual fibers contained within a single jacket or buffer tube. Also a group of buffered fibers distinguished in some fashion from another group in the same cable core. Cable Assembly: Optical fiber cable that has connectors installed on one or both ends. Cable Bend Radius: The radius that a fiber can be bent before risking increased attenuation or fiber breaks. Central Member: A material located in the middle of a cable that provides extra strength and anti-buckling properties. Chromatic Dispersion: Spreading of a light pulse caused by the difference in refractive indices at different lengths. Cladding: Dielectric material surrounding the core of an optical fiber. Connector: A passive device attached at the end of a fiber to couple light from a transmitter to a receiver or between two fibers. Connector Return Loss: Amount of power reflected from the connector to connector interface, typically expressed in decibels. Core: Central region of an optical fiber through which light is transmitted. Core Eccentricity: Measure of the displacement of the center of the core relative to the cladding center. Core Ellipticity: Measure of the nonroundness of the core. Coupling Efficiency: Efficiency of optical power transfer between two components. Coupling Loss: Power loss suffered when coupling light from one optical device to another. Critical Angle: Smallest angle at which a meridional ray may be totally reflected within a fiber at the corecladding interface. Crosstalk: Phenomenon of unwanted light transfer between fibers. CSA: Abbreviation for Canadian Standards Association. Decibel (dB): Standard unit used to express the magnitude of signal gain or loss. Dielectric: Any non-metallic, nonconductive material. Diffraction: Phenomenon that results when light passes by an opaque edge or through an opening, generating weaker secondary wavefronts. These secondary wavefronts interfere with the primary wavefronts, as well as with each other, to form various patterns. Digital: Data format that uses two physical levels, ones and zeros, to transmit information. 51