How Fibre-Optic Cable Works
The glass or plastic used in fibre-optic cable is manufactured to be pure and without any imperfections so that the light signal can travel without hindrance over long distances, e.g. miles. The fibres or threads are extremely thin strands; about as thick as human hair, coated with two layers of highly reflective plastic that creates an internal mirror around the strand. The outer sheath works as mirror causing an internal reflection that light cannot escape from and is thus guided along bouncing off at shallow angles. This principle is known as total internal reflection.
At both ends of the fibre link there are photodiodes which must be in exact alignment in order to prevent signal reflection. The means of placing the signal on the fibre can be carried out by Light Emitting Diode (LED) or an Injection Laser Diode (ILD).
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