A chemical compound that is the most common
substance used in the manufacture of optical fiber
for doping the fiber core.

Interference in the backscatter diagram as the result
of multiple reflections on the fiber link

Fiber with a gradient index profile

Glass rod a few millimetres in diameter which has
a refractive index curve like that of a parabolic index
fiber (profile exponent ≈ 2). The light propagates
in an approximately sinusoidal shape. In fiber optic
technology, GRIN lenses are used imaging elements
or in beam splitters.

Quotient from velocity of light in vacuum and
propagation velocity of a wave group (group velocity),
of a light pulse in a medium.

Propagation velocity of a wave group, e.g. of a light
pulse, which is composed of waves having different
wavelengths.