Figure 2. Total internal reflection in an optical fiber.
Optical fibers are divided into two groups called single
mode and multimode. In classifying the index of refraction
profile, we differentiate between step index and gradient
index. Step index fibers have a constant index profile over
the whole cross section. Gradient index fibers have a
nonlinear, rotationally symmetric index profile, which falls
off from the center of the fiber outwards [14]. Figure 3
shows the different types of fiber