16-10-2010, 07:03 PM
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FIBRE OPTIC COMMUNICATION
Surasak Sanguanpong
nguan[at]ku.ac.th
brief explanation
There are basically two modes of a transmission in a fiber. A multimode fiber
has a number of paths in which light ray may travel. A single mode has a
light ray in one direction only.
Fibers are further classified by the refractive index profile of their core. They
can be either step index or graded index. Three main types of fibers are
multimode step-index fiber , multimode grades index fiber and single mode
fiber.
The refraction index of multimode step-index fiber is uniformly throughout
the core. The refraction index of multimode graded-index fiber is gradually
less dense), light travels radically outward it begins to bend back toward the
center, eventually reflecting back. Because the material also less dense, the
light travels faster. Reducing the core diameter to that of a single wavelength
(3-10 will let the light propagates along a one mode only.