Cable Assembly (fiber optic): A cable that is terminated on both ends with connectors.

Cable Plant (fiber optic): All of the components between the transmitter and the receiver.

Chromatic Dispersion: A reduction in the bandwidth of a fiber caused by different wavelengths of light traveling at different speeds through the fiber.

Cladding: The material that surrounds the core material in an optical fiber. The cladding has a lower index of refraction than that of the core causing the light beam to reflect and travel into the core.

Cleave: A process by which the fiber is nicked to produce a controlled fracture of the glass,resulting in a clean,flat,smooth end that is nearly perpendicular to the fiber axis.

CWDM (Coarse Wavelength-division Multiplexing):Stacking 8 or fewer channels within the 1550nm region of optical fiber.

Coating: The material surrounding the cladding of an optical fiber,protecting it from damage.

Concatenation:Connecting multiple pieces of fiber.

Concentricity (optical fiber):The measurement of the offset between the center of the core and the center of the cladding.

Concentricity (fiber optic connector):The measurement of the offset between the center of the connector ferrule and the center of the connector hole in the ferrule.

Connector (fiber optic):A mechanical device that allows for connection and disconnection between two fibers (or fiber and source or fiber and detector).

Core:The portion of the fiber that transmits light.The core has a higher index of refraction than the cladding.

Coupler:An optical device that combines or splits power between optical fibers.

dB (Decibel):A unit of measurement of relative power on a logarithmic scale.

dBm:Abbreviation to decibel relative to milliwatt.

Dense Wavelength Division Multiplexing (DWDM):The transmission of many closely spaced wavelengths in the 1550nm region over a single fiber.

Detector (fiber optic):The opto-electric device that converts an optical signal into electrical current.

Diameter mismatch loss:Attenuation caused by mating two optical fibers having different core diameters,when the light is propagated from the large core into the small core.

Dielectric:A substance which does not conduct or transmit electrical current (in fiber optics,this usually refers to cable with no metallic materials).

Dispersion:The spreading of a light signal in an optical fiber caused by light signals traveling at different speeds through the fiber,due to either modal or chromatic effects.

Dispersion-shifted Fiber (DSF):A type of singlemode fiber designed to have zero dispersion near 1550nm.

Dual-window fiber:Fiber optimized to operate at more than one wavelength (typical multimode at 850nm and 1300nm and singlemode at 1310nm and 1550nm).

Duplex Cable:A cable with two fibers,typically designed for interface between transmission equipment and cable plant (transmit/receive).