Page 56 - Optical Switching And Networking Handbook

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Basic Fiberoptics Technologies 41

ter the grading of the index, the more throughput you can expect.
Currently, the two forms of graded index fiber use either a 62.5- or
a 50-micron center conductor with a 125-micron outer cladding on
the glass.
Here, an analogy also will help with understanding. We can neu-
tralize the effects of the thick and thin glass by creating a different
resistance factor. If the thin glass is in the outer edge and the thicker
glass is in the center, the values can be neutralized. This gives us an
average speed. Think of a racetrack. The summer Olympic games
use this effect when they set the stage for foot races. If you are run-
ning on the outer edge of a racetrack, the diameter of the oblong that
you are running is greater than if you are running at the center of
the track.To compensate for this, the runners are spaced at different
points on the track, with the longest length having what appears to
be a lead at the starting block, as shown in Figure 2-9. In reality, all
the runners have to run the same distance; they just have to do it dif-
ferently. However, the speed of the runners is what separates the
racers, not the lengths of the oblong rings.These have been averaged

Starting positions are jogged to
Figure 2-9 accommodate distance differences,
Geometry of the yielding dual distances to be covered.
track is adjusted to
equalize the
distances.

lane 4
lane 3
lane 2
Lane 1

lane 1

Finish Line