Did you know: Fibre optics in Namibia

Text Bill Torbitt

Fish-eye view

If you swim underwater and look up towards the surface, you will see a circle of light into which the whole image of the outside world is concentrated. Beyond that, however, you see nothing but a reflection of the bottom of the pool. This is known as the ‘fish-eye view’.

The laws of reflection

When a ray of light crosses from a ‘dense’ medium (water or glass) to a less dense one (air), it is bent away from the perpendicular direction. It follows that if the light strikes the boundary between the media at a sufficiently slanting angle, the light cannot escape at all, and is totally reflected back into the denser medium. In the pool, it is as if the under surface of the water was a perfect mirror.

Refraction of light

This has been known ever since Newton discovered the laws of reflection and refraction of light. For an underwater swimmer, it might be thought a nuisance, but in fact it is incredibly useful. You might say that modern Internet civilisation now depends on it. Because if a ray of light is sent down a narrow glass rod, the ray cannot get out – it is like a snake wriggling along in a pipe. If it is travelling a little off-straight and hits the side of the rod, it will surely be at a very glancing angle, and so will be reflected back into the rod. Even if the rod is moderately curved or bent, the same will apply.

Incredibly thin glass fibres

Of course, we do not use water or thick glass rods, but incredibly thin glass ‘fibres’, only a few thousandths of a millimetre thick. These fibres are flexible and quite tough, although they have to be encased in a ‘cladding’ material. If made of very pure transparent silica glass, light can travel down the fibre for kilometres, even hundreds of kilometres, without being degraded. And, of course, light travels down the fibre very fast, almost at the speed of light, by definition. To send actual information down the fibre – telephone calls, websites, videos or emails – we only have to ‘modulate’ the light in the same way that we do for radio waves. If the light (and the signal) does eventually become dim, we can amplify it in a clever way that resembles laser action – there is no need to use an electronic amplifier.

Namibia’s fibre infrastructure

This ‘fibre optic technology’ has revolutionised telecommunications over short and long distances, and Namibia has a very sophisticated fibre infrastructure. If you look closely at traditional telegraph poles next to country roads, you will see they carry no wires. They have not done so for some years – their function being replaced by underground fibre optic cables. And optic fibre has many advantages over traditional copper tabling – copper is expensive, heavy and unfortunately a target for thieves. Fibre offers better security, because it is much more difficult to ‘tap’ a fibre than a copper wire. But most importantly, optic fibre can carry vastly more data at much higher speeds than metal wires. The whole globe is connected by undersea fibres linking the continents.

Fibre to the home

There are many ongoing fibre projects in Namibia. Namibia Telecom is steadily expanding its nationwide fibre network – the ultimate objective being FTTH or ‘fibre to the home’, eliminating old copper communications completely, and the perennial telephone problems during rainy weather. The leading mobile operator is engaged in laying fibres through urban Windhoek, an infrastructure essential to its 4G project. Most excitingly, Namibia was connected last year to the WACS system – an ultra-high capacity fibre cable linking South Africa, Namibia and western African countries to London. Tourists watching the cable-laying vessel just off shore in Swakopmund, thought it might be an ‘invasion’.  It is, in a way, a technological invasion that will help the peoples of Namibia and Africa to derive full benefit from the age of the Internet.

This article appeared in the April 2012 edition of FLAMINGO Magazine.