Into the Future at the Speed of Light

Some of the first copper cables are probably still lying around or installed in old houses. For a long time, they did their job well and – principally speaking – still could. But traffic has increased dramatically since that time. Like the streets of city centres, traffic jams inevitably occur during rush hour. What do the future data traffic networks look like?

Why is an Optical Fibre Faster Than a Copper Cable?

“Which is faster? Copper or fibre?” If you ask this question to passers-by on the street today, the answer will almost always be: “Optical fibre, of course.” But is that really true? And if it is true, why is that? As usual in science and technology, the answer is more complex; however, it is also more exciting than expected.

It is important to point out that in both cases we are talking about digital signal transmission. In the copper cable, the “zeros and ones” of the digital code are transmitted by electrical signals. Simply put, the current is switched on and off again and again. In an optical fibre (Fibre Optic Cable), this transmission functions with the help of light. At first glance, you might say: “Then it is pretty clear because, as we know, nothing is faster than light.” That is of course correct, but it is also true that all electromagnetic waves travel at the speed of light, including electricity and radio waves. So why is light still the better transmission path in this case?

Higher Data Throughput

The number one issue is bandwidth. In industry jargon, this refers to data rate, which is the amount of information that is transmitted in one second. At a bandwidth of around 10 Gbit/s, cable television networks (CATV) are the most capacity copper networks. Depending on the type of fibre, optical signal transmission now allows several Tbit/s. In addition, technology today makes it possible to transmit many signals through the same fibre by assigning a specific wavelength (colour) to each signal. There are now networks available that support up to 160 colours simultaneously.

Longer Range

Another advantage of fibre optics is their low attenuation. With the high-quality fibres available today, distances of up to 120 km can be bridged with little signal loss. With copper cables, however, an electrical signal amplifier must be installed every 500 metres or so. This makes network expansion much more complicated and, on top of that, costs energy and money.

Interference Free

Most optical fibres are made of quartz glass, which is a brittle and sensitive. Copper, however, can be shaped almost at will. So, what material advantages should optical fibres offer? Quite simply, quartz glass is non-conductive and therefore resistant to electromagnetic influences. Copper, on the other hand, is one of the best conductors of all. Therefore, signal interference can always occur. Interference can be caused, for example, by nearby thunderstorms or simply by electrical devices that are operated in the vicinity. The phenomenon of “crosstalk,” in which conversations conducted on neighbouring lines at the same time overlap each other, is also well known.

Temperature changes have little effect on optical fibres. This is illustrated by the fact that if copper is heated, its electrical resistance increases and inhibits signal transmission. A similar effect does not occur with optical fibres.

Future Proof

Although they are more expensive to manufacture, optical fibres are becoming more economical as bandwidth requirements increase, especially since the fibres and network components are comparatively low maintenance. Best of all, the technology is scalable for the foreseeable future. The networks can be adapted to the constantly growing bandwidth requirements with little effort because the fibres and splitters can continue to be used unchanged. Only the end devices may need to be replaced.

And How Do the Fibres Get into the Home?

When will the average citizen be able to enjoy this fabulous technology? the answer is a bit more complex than the question:

Just picture a fibre optic network like you would a tree, in which water is distributed from the trunk, through smaller and smaller branches and twigs, to the individual leaves. In telecommunications, the trunk is referred to as the backbone or transport network. The leaves would be the so-called subscriber lines (i.e., the connection sockets) to which the user connects their terminal equipment (router, telephone, computer, television, ...). The transport network now consists almost exclusively of optical fibres, the closer we get to the leaves of the tree, the more frequently we still encounter copper cables. The so-called “last mile” (i.e., the distance from the familiar grey distribution box at the roadside to the user’s home) is currently considered particularly critical.

In Germany the Association of Telecommunications and Value-Added Service Providers (VATM) states that at the end of 2020, around 1.87 million of 41.5 million households nationwide were supplied with optical fibres. This corresponds to just 4.5% of households. However, the industry association also assumes that the network will be expanded to around 25 million households by 2026. The federal government’s broadband funding programme is providing around EUR 12 billion for the expansion, which is to be used primarily in areas where data rates are still below 100 Mbit/s. This means a lot of work for the companies involved. The effort is well worth it because fast internet is the key to the digital future.