Fibre is not just good for the body

Fibre optic lines have, over the last decade or so, taken over and completely transformed the long distance phone industry. Optical fibres are also a massive part of making broadband available, not just in the United Kingdom, but around the world. When fibre optic lines replace copper for long distance calls and Internet traffic, it can dramatically lower the cost. Many people with fibre optic broadband will have used it to buy cheap landlord insurance without the need to speak to anyone, and in a high tech world landlords often get enquiries from prospective tenants on the availability of broadband in the property to be rented.

To fully understand how a fibre optic cable works, just imagine an extremely long straw or even flexible plastic pipe. Now, imagine that the pipe that is quite a few miles long. Imagine that the inside of the pipe has been coated with a perfect mirror. Imagine yourself looking into one end of the flexible plastic pipe. While several miles away at the other end of the pipe someone turns on a torch and shines it into the pipe. Because the interior of the pipe is a perfect mirror, the light from the torch will reflect off the sides of the pipe, this will happen even if the pipe curves and twists and the light will be visible at the other end. If the person at the other end were to turn the torch on and off like a Morse code signal, it would be possible for two people to communicate through the pipe. That is the essence of a fibre optic cable.

It would be possible to make cable out of a mirrored tube, but the result would be bulky and it would also be very difficult to coat the inside of the tube with a perfect mirror. Because of this, a real fibre optic cable is made out of glass. The glass it self is incredibly pure and even though it is several miles long, light can still make it through. The glass is then drawn into a very thin strand, so thin in fact that it is similar to the thickness of a human hair. This thin glass strand is then coated in two layers of plastic. By coating the glass in plastic, it gives the equivalent of a mirror around the thin glass strand. This mirror will create a total internal reflection, just like the perfect mirror coating on the inside of a tube has done. Today’s fibre optic cables can carry a signal quite some distance, maybe 60 miles. If it is a long distance line, there will be some kind of equipment hut every 40 to 50 miles. This hut will contain equipment that will pick up and then re-transmit the signal down the next segment to the next hut at full strength.

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