Cable assembly - Fiber optic cable that has connectors installed on one or both ends. General use of these cable assemblies includes the interconnection of multi-mode and single-mode fiber optic cable systems and opto-electronic equipment. If connectors are attached to only one end of the cable, it is known as a pigtail. If connectors are attached to both ends, it is known as a jumper.
Cable bend radius - During installation this infers that the cable is experiencing a tensile load. Free bend infers a lower allowable bend radius since it is at a condition of no load.
Carrier Sense Multiple Access With Collision Detection CSMA/CD - A technique employed in Ethernet based LANs to control the transmission channel. It assures that there is no conflict between terminals that wish to transmit.
Center wavelength - The wavelength of an optical source that might be considered its middle. One measure of this is the average of the 2 wavelengths corresponding to the Full Width Half Maximum- FWHM.
Central member - The center component of a fiber optic cable. It serves as an anti-buckling element to resist temperature-induced stresses. Sometimes serves as a strength element. The central member is composed of steel; fiberglass or glass reinforced plastic.
Central office - CO. The places where communications common carriers terminate customer lines and locate switching equipment that interconnects those lines. It is the lowest hierarchical level of a TELCO backbone network. It is from the Central office level that local loops go out to end-user customer premises equipment.
Centro-symmetrical Reflective Optics - An optical technique in which a concave mirror is used to control coupling of light from 1 fiber optic cable to another.
Channel - A communications path derived from a specific transmission medium, as for example fiber optic cables. The channel supports the end-to-end communications of an information source and destination. Besides the transmission medium a channel needs to have a transmitter/receiver (transceiver) and a modulator/demodulator (modem). By multiplexing, several channels can share the same specific transmission medium. Channel is synonymous with link. The term channel is usually employed within the context of multiplexing- but not always.
Chromatic bandwidth - The inverse of the Chromatic Dispersion.
Chromatic dispersion - The speed of an optical pulse travelling down a fiber optic cable changes if the wavelength changes. However, any practical light source has a spectral width that is, has components at a number of different wavelengths. This results in a pulse broadening - the time width of pulse broadens as it propagates down a fiber optic cable. This effect is called chromatic dispersion. It can be calculated experimentally by measuring the travel time down a fiber optic cable of light at different wavelengths.
Cladding - A low refractive index glass or plastic that surrounds the core of the fiber optic cable. Optical cladding promotes total internal reflection for the propagation of light in fiber. The cladding steers light to the core.
Cladding modes - A mode that is confined to the cladding. Basically, a light ray that propagates down the cladding. Attenuation is very high in the cladding. Consequently, a cladding mode is eliminated after a few meters.
Cleaving - The controlled breaking of a fiber so that its end surface is smooth.
Club Des Fibres Optiques Plastiques - Club formed in
Coating - A material put on a fiber optic cable during the drawing process to protect if from the environment.
Coherent light or light waves - This is light of which all parameters are predictable and correlated at any point into time or space, particularly over an area perpendicular to the direction of propagation or over time at a particular point in space. Simply, coherent light usually refers to the phenomenon relating to the existence of a correlation between the phases of the corresponding components of 2 light waves or to the values of the phase of a given component at 2 instants in time or 2 points in space. Coherent light does not occur naturally in the Universe. It can only be generated a laser.
Concentrator - A multi-port repeater.
Conduit - Pipe or tubing through which cables can be pulled or housed.
Connector - A mechanical device mounted on the end of a fiber optic cable, light source, receiver or housing that mates to a similar device. It allows light to be coupled, optically, into and out of a fiber optic cable. A connector allows a fiber optic cable to be connected or disconnected repeatedly from a device. Commonly used connectors include FC/PC,
Connector insertion loss - See Insertion Loss.
Connector-induced fiber loss - That part of the Conductor Insertion Loss, expressed in dB, due to impurities or structural changes to the fiber optic cable by termination or handling with the connector.
Core - The central, light carrying, part of a fiber optic cable. It has an index of refraction higher than that of the surrounding cladding.
Core eccentricity - A measure of the displacement of the center of the core relative to the cladding center.
Coupler - It is used in 2 contexts. First, it is a passive device that distributes optical power among 2 or more ports and this can be in different ratios. Secondly, it is a multi-pod device used to distribute optical power.
Coupling efficiency - The efficiency of optical power transfer between 2 components.
Coupling losses - The power loss suffered when coupling light from one optical device to another. There are intrinsic losses (non-ideal fiber parameters) and extrinsic losses (mechanical effects).
Coupling ratio - The percentage of light transferred to a receiving output port with respect to the total power of all output ports.
CPE - Customer Premises Equipment.
Critical angle - The greatest angle of incidence for which a wave propagating in a homogeneous medium of relatively high refractive index strikes an interface with a medium having a lower refractive index and for which refraction in just possible. With respect to fiber optic cabling the critical angle is therefore the smallest angle at which a light ray will be totally reflected within the fiber and thereby guided down the fiber - total internal reflection.
Crosstalk - The pickup in one particular fiber optic cable of unwanted light from another fiber optic cable.
CSMA/CD - Carrier Sense Multiple Access with Collision Detection.
CSR - Centro symmetrical reflective optics.
Cutback - A method for measuring the attenuation or bandwidth of a fiber optic cable by first measuring the full length and then cutting back and measuring, again, the fiber optic cable at a shorter length.
Cut off wavelength - For a single mode fiber optic cable it is the wavelength above which the fiber optic cable exhibits single mode operation.
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