Introduction to Fiber Optics, 3rd Edition

Have a look at Figure 4.1. What path would be taken by the incoming ray?

Would it finish up at A or B?

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4

Propagation of light

along the fiber

C

r

i

t

i

c

a

l

a

n

g

l

e

Normal

Incoming

ray

A length of optic fiber

A

B

Figure 4.1

Does the ray

go to A or B?

In Chapter 2 we saw that light approaching the outer edge of the optic fiber at

an angle greater than the critical angle would be reflected back into the fiber

and would bounce its way along as in the ray path B.

This diagram suggests that a useful transmission system can be built from a simple

length of clear glass. Unfortunately, it is not that straightforward – as soon as we

touch the fiber, we transfer some grease from ...