Glossary
Term | Main definition |
---|---|
Diameter mismatch loss |
The loss of power that occurs when one fiber transmits to
another and the transmitting fiber has a diameter greater
than the receiving fiber. It can occur at any type of coupling
where the fiber/coupling sizes are mismatched:
fiber-to-fiber, fiber-to-device, fiber-to-detector, or sourceto-
fiber. Fiber-optic cables and connectors should closely
match the size of fiber required by the equipment.
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Diamond Network / Programme | MBNL Network improvement / consolidation programme.
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Dichroic filter |
Selectively transmits or reflects light according to
selected wavelengths. Also referred to as dichromatic
mirror.
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Die Cast | (see Shielded hood)
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Dielectric |
Material that does not conduct electricity, such as nonmetallic
materials that are used for cable insulation
and jackets. Optical fiber cables are made of dielectric
material.
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Dielectric constant |
The property of a dielectric material that determines the
amount of electrostatic energy that can be stored by the
material when a given voltage is applied to it. The ratio
of the capacitance of a capacitor using the dielectric to
the capacitance of an identical capacitor using a vacuum
as a dielectric. Also called permittivity.
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Dielectric loss |
The power dissipated in a dielectric material as the result
of the friction produced by molecular motion when an
alternating electric field is applied.
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Dielectric nonmetallic |
Refers to materials used within a fiber-optic cable.
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Differential group delay (DGD) |
The total difference in travel time between the two
polarization states of light traveling through an optical
fiber. This time is usually measured in picoseconds, and
can differ depending on specific conditions within an
optical fiber and the polarization state of the light passing
through it.
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Differential modal dispersion (DMD) |
The test method used to determine the variation in
arrival time of modes in a pulse of light in an optical
fiber (typically for multimode fiber).
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Differential mode attenuation |
A variation in attenuation in and among modes carried
in an optical fiber.
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Diffraction |
The deviation of a wave front from the path predicted
by geometric optics when a wave front is restricted by
an edge or an opening of an object. Diffraction is most
significant when the aperture is equal to the order of the
wavelength.
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Diffraction grating |
An array of fine, parallel, equally spaced reflecting or
transmitting lines that mutually enhance the effects of
diffraction to concentrate the diffracted light in a few
directions determined by the spacing of the lines and by
the wavelength of the light.
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Diffuse infrared |
It enables the use of infrared optical emissions without
the need for line-of-sight between the transmitting and
receiving communication entities.
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Digital |
Refers to transmission, processing, and storage of data
by representing the data in binary values (two states:
on or off). On is represented by the number 1 and off by
the number 0. Data transmitted or stored with digital
technology is expressed as a string of 0s and 1s. Digital
signals are used to communicate information between
computers or computer-controlled hardware.
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