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Fibre is forever?

The roll-out of the UFB marks a quantum leap in the levels of connectivity available to domestic users.

From the paltry 300bps of acoustically coupled modems that were all we had some 40 years ago, through to the 56Kbps which became the speed limit imposed by Shannon's Law, copper is now well past its "best-by" date.

Although advanced copper-based technologies such as VDSL can deliver fairly decent speeds over short distances, the many other problems of copper remain. Easily affected by rain, lightning, corroded connections, etc -- copper really is no match for fibre.

What's more, ongoing advances in the way we squeeze more bandwidth out of the same length of optical fibre look set to ensure that the useful lifespan of glass may exceed that of copper by a significant margin.

An example of this ever-improving technology can be seen in this Science Daily story in which it is reported that researchers at Caltech have been able to significantly improve the spectral purity of solid state lasers.

To understand how important this is we must remember that the light spectrum available for use via fibre is divided by frequency and, just like the various stations on your radio dial, different light frequencies can be used simultaneously to deliver different data streams.

One way to increase the amount of data a piece of fibre can carry is to use different lasers of different wavelengths (colours). Indeed, this strategy has already enabled old fibre to carry far more data than was possible when it was first laid.

However, the big breakthrough that the Caltech guys seem to be working on is a method of changing the way the laser light is modulated so as to squeeze even more data out of the same amount of spectrum.

By creating an even more coherent light source, they can now use phase modulation (very similar to frequency modulation) to encode more data than was possible with the old off/on amplitude modulation previously used.

All this has made it even more obvious that the fibre we're laying is presently used to only a tiny percentage of its true potential -- leaving plenty of room to dramatically boost its bandwidth as demand requires it.

Although our demand for data bandwidth seems to be growing at an almost exponential rate, I think it's safe to say that the fibre we're laying right now will serve us for at least as many generations as the copper that went before it.

The next question will probably be... "what can we use all this bandwidth for?"

Hmmm... more reality TV perhaps?

Aaaargh -- bring back the copper! :-)

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