Researchers integrate high speed electronic functions into optical fibre

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Researchers have, for the first time, developed crystalline materials that enable an optical fibre to have integrated, high speed electronic functions.

According to scientists from the University of Southampton, potential applications of such optical fibres include improved telecommunications/hybrid optical and electronic technologies, improved laser technology and more accurate remote sensing devices. The university developed the materials with Penn State University and will publish their findings in Nature Photonics. In a bid to embed the high level of performance normally associated with chip based semiconductors into an optical fibre, the team built an optical fibre with a high speed electronic junction – the active boundary where all electronic 'action' takes place – integrated adjacent to the light guiding fibre core. They discovered that light pulses (white spheres) travelling down the fibre could be converted to electric signals (square wave) inside the fibre by the junction. Rather than merging a flat chip with a round optical fibre, a new way to build a new kind of optical fibre with its own integrated electronic component was discovered. This bypassed the need to integrate fibre optics onto a chip and was achieved by using high pressure chemistry techniques to deposit semiconducting materials layer by layer directly into tiny holes in optical fibres. Dr Pier Sazio, senior research fellow in the University of Southampton's Optoelectronics Research Centre (ORC), said: "The big breakthrough here is that we don't need the whole chip as part of the finished product. We have managed to build the junction - the active boundary where all the electronic action takes place - right into the fibre. Moreover, while conventional chip fabrication requires multimillion dollar clean room facilities, our process can be performed with simple equipment that costs much less." John Badding, professor of chemistry at Penn State, added: "The integration of optical fibres and chips is difficult for many reasons. First, fibres are round and cylindrical, while chips are flat, so simply shaping the connection between the two is a challenge. Another challenge is the alignment of pieces that are so small. An optical fibre is 10 times smaller than the width of a human hair. On top of that, there are light guiding pathways that are built onto chips that are even smaller than the fibres by as much as 100 times, so imagine just trying to line those two devices up. That feat is a big challenge for today's technology." According to the researchers, the technology also has many potential non-telecommunications applications. It represents a very different approach to fabricating semiconductor junctions that the team is investigating. ORC postdoctoral researcher, Dr Noel Healy noted: "This demonstration of complex in fibre optoelectronic engineering is exciting, as it has the potential to be a key enabling technology in the drive for faster, lower cost, and more energy efficient communication networks."