Macroscopic axial deviations in a fiber from a straight
line (e.g. on a delivery spool). Can lead to local attenuation,
particularly in singlemode fibers if certain radii
of curvature are exceeded.

Microscopic bends or unevenness in the fiber
which give rise to losses by injecting light
that is guided in the core into the cladding.

Component that contains moving mechanical parts
to guide light. Two-dimensional and three-dimensional
configurations are possible.

The dispersion in a fiber caused by the superimposition
of modes having different delay times at the same
wavelength. Dominant type of dispersion in a multimode
fiber.

Measure of the width of the approximate Gaussian
light distribution in a singlemode fiber. It is the distance
between the points at which the field distribution
drops to the value 1/e ≈ 37 %. Since the eye
records the intensity of the light, the mode field diameter
corresponds to a drop in intensity, with respect
to the maximum value, to 1/e2 ≈ 13.5 %.

Component for implementing an approximate
equilibrium mode distribution. It causes radiation
of higher-order modes.

Gradual energy exchange between the various modes
during the propagation along the multimode fiber.

Component for implementing an equilibrium mode
distribution in a multimode fiber.

Solutions to Maxwell's equations, taking into account
the constraints of the waveguide. They correspond
to the possible propagation paths in the fiber.

A selective change in a parameter (amplitude, phase
or frequency) of a harmonic or discontinuous carrier
in order to transmit a message by this carrier.

Fiber whose core diameter is large compared
with the wavelength of the light. Numerous modes
can be propagated in it.

Interference as a result of multiple reflections on one
optical path. These reflections are phase-shifted within
the detected signal, which results in pulse spreading
and a deterioration of the system properties.

Functional unit that receives a series of transmission
channels and bundles the signals for transmitting
in a common channel. At the end of a section,
a demultiplexer separates them back into the original
signals. A distinction is made between various
multiplexing methods, e.g. time-division multiplexing
or wavelength-division multiplexing.