GLOSSARY
11
ABSORPTION
Loss of power in an optical fiber, resulting from conversion of optical power into
heat and caused principally by impurities, such as transition metals and hydroxyl
ions, and also exposure to nuclear radiation.
ANGLE OF INCIDENCE
Angle between the incident ray and the normal.
ANGLE OF REFRACTION
Angle between the refracted ray and the normal.
ATTENUATION
A general term indicating a decrease in power from one point to another. In
optical fibers, it is measured in decibels per kilometer at a specified wavelength.
BANDWIDTH
A range of frequencies.
CABLE
A fiber covered by a protective jacket.
CAPACITOR
A capacitor stores electrical energy when charged by a DC source. It can pass
alternating current (AC) but blocks direct current (DC) except for a very short
charging current, called transient current.
CLADDING
The outer concentric layer that surrounds the core and has a lower index of
refraction.
CONNECTOR
A connector is a device which is used to connect both ends of the fiber to the
source and detector.
CORE
The central, light-carrying part of an optical fiber; it has an index of refraction
higher than the surrounding cladding.
dB
Decibel.
DECIBEL
A standard logarithmic unit for the ratio of two powers, voltages or currents. In
fiber optics, the ratio is power. dB = 10 log
10
(P
1
/P
2
)
ELECTROMAGNETIC
INTERFERENCE
Any electrical or electromagnetic energy that causes undesirable response,
degradation, or failure in electronic equipment. Optical fibers neither emit nor
receive EMI.
EMI
Electromagnetic interference.
FIBER
A light-carrying conductor made up of glass or plastic.
INDEX OF REFRACTION
The ratio of the velocity of light in free space to the velocity of light in a given
material. Symbolized by n.
11 The “GLOSSARY” Section is reproduced by permission TECHNICIAN’S GUIDE TO FIBER OPTICS 2E (PAGES 256-264)
By Donald J Sterling, Jr. - DELMAR PUBLISHERS, INC., Albany, New York, Copyright 1993
-21-
