Fibre optics (optical fibres) are long, thin strands of pure glass about the diameter of a human hair.
They are arranged in bundles called optical cables and used to transmit light signals over long distances. The bundles are protected by the cable's outer covering, called a jacket.
Optical fibres come in two types:
- Single-mode fibres have small cores (about 3.5 x 10-4 inches or 9 microns in diameter) and transmit infrared laser light (wavelength = 1,300 to 1,550 nanometres).
- Multi-mode fibres have larger cores (about 2.5 x 10-3 inches or 62.5 microns in diameter) and transmit infrared light (wavelength = 850 to 1,300 nm) from light-emitting diodes (LEDs).
How does an optical fibre cable work?
Suppose you want to shine a flashlight beam down a long, straight hallway. Just point the beam straight down the hallway - light travels in straight lines, so it is no problem, but what if the hallway has a bend in it?
You could place a mirror at the bend to reflect the light beam around the corner. What if the hallway is winding with multiple bends? You might line the walls with mirrors and angle the beam so that it bounces from side-to-side all along the hallway. This is exactly what happens inside an optical fibre cable.
The light in a fibre-optic cable travels through the core (hallway) by constantly bouncing from the cladding (mirror-lined walls), a principle called total internal reflection. Because the cladding does not absorb any light from the core, the light wave can travel great distances.
Fibre optic cables are available from Dueltek Computer Products .