Smart fibre follows its own logic

Breakthrough allows transistor lining to do the work of switches and modulators in optical links

Researchers have found a way to create smart optical fibre capable of performing tasks currently done by external electronics.

They have managed to create a transistor within a fibre just five millionths of a metre in diameter by injecting vaporised germanium at very high pressure to create a thin layer of crystallised semiconductor.

The work done at Southampton University's Optoelectronics Research Centre in Britain, and Penn State University in the US, is essentially a proof of concept which should lead to more complex devices.

Pier Sazio, a research fellow at Southampton and lead author of a report on the work in Science, said the technique could be used to create modulators, which translate an electronic signal into an optical one, or switches.

'The leap forward is to engineer rich optoelectronic functionality inside an optical fibre,' he said.

One of the basic building blocks of fibre links and the Internet, the erbium-doped fibre amplifier, was invented at Southampton in 1986; it allows optical signals to be amplified without going through a slower electronic process.

Another breakthrough announced this week, a fast organic transistor, was also co-developed at Southampton.