FO600 Datasheet, PDF (50/57 Pages) Extech Instruments Corporation. – FiberMeter Optical Power Meter

UNIT 5
Appendices
Glossary, cont.
Light-Emitting Diode (LED). A semiconductor diode that spontaneously emits light from the PN junction when
forward current is applied.
Main Cross-Connect (MC). The cross-connect in the main equipment room for connecting entrance cables,
backbone cables, and equipment cables.
Material Dispersion. Dispersion resulting from the different velocities of each wavelength in an optical fiber.
Modal Dispersion. Dispersion resulting from the different transit lengths of different propagating modes in a
multimode optical fiber.
Mode. A possible path followed by light rays.
Multimode Fiber. A type of optical fiber that supports more than one propagating mode.
Numeric Aperture (NA). The number that expresses the light-gathering ability of a fiber.
Optical Time Domain Reflectometry (OTDR). A method of evaluating optical fibers based on detecting
backscattered (reflected) light. Used to measure fiber attenuation, evaluate splice and connector joints, and
locate faults. Also, the equipment used to perform such measurements (Optical Time Domain
Reflectometer).
Photodetector. An optoelectronic transducer, such as a PIN photodiode or avalanche photodiode.
Photodiode. A semiconductor diode that produces current in response to incident optical power and used as
a detector in fiber optics.
Photon. A quantum of electromagnetic energy; a particle of light.
Receiver. An electronic device which converts optical signals to electrical signals.
Responsivity. The ratio of a photodetector’s electrical output to its optical input in an optical fiber.
Singlemode Fiber. An optical fiber that supports only one mode of light propagation above the cutoff
wavelength.
Source. The light emitter, either an LED or laser diode, in a fiber optic link.
Spectral Width. A measure of the extent of a spectrum. For a source, the width of wavelengths contained in
the output at one half of the wavelength of peak power. Typical spectral widths are 20 to 60 nm for an LED and
2 to 5 nm for a laser diode.
Splice. An interconnection method for joining the ends of two optical fibers in a permanent or semi-
permanent fashion.
Step-Index Fiber. An optical fiber, either multimode or single mode, in which the core refractive index is
uniform throughout so that a sharp step in refractive index occurs at the core-to-cladding interface. It usually
refers to a multimode fiber.
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