EU-funded researchers develop new plastic optical fibre technology
Plastic optical fibre (POF) is making headway in the technology world and the EU-funded POLYCOM ('Plastic optical fibres with embedded active polymers for data communications') project has played a central role in its success. Backed with EUR 1.55 million under the 'Information Society Technologies' (IST) Thematic area of the EU's Sixth Framework Programme (FP6), POLYCOM has promoted the use of POF in optical computing, ultra-high-speed LANs (local area networks) and new sensing devices. POF for data transmission is known as the 'consumer' version of glass optical fibre, and is used in the long-distance trunk routes of global telecommunications networks. Flexible plastic fibres, which are produced by polymethyl methacrylate (PMMA) and have a core diameter of one millimetre (mm), are unique in that their production costs are low, their installation is simple and trouble-free, and their light transmission is safer and easier to maintain than infrared versions. The downside is that their use is limited to short-distance and low-speed data transmission. 'The range of applications for POF and the optical technology that underlies it is extensive, and its development beyond the current state of the art could benefit a wide range of sectors over the coming years,' said Guglielmo Lanzani of the Milan Technical University in Italy, and coordinator of POLYCOM. The POLYCOM consortium, comprising six partners from Germany, Italy, Portugal and the UK, succeeded in developing the first-ever all-optical high-speed switch for POF networks. This groundbreaking result will fuel the research sector's and industry's need for fast optical data transmission. The project partners tested the technique by using two beams of light from a single pulsed laser source in a special plastic optical fibre. The physical properties of the plastic optical fibre were altered chemically, or doped, with photoactive polymers to modify the transmission of photons. According to the researchers, one light pulse could be used to cancel out the other since they overlapped the light pulses in space and time. The end result was that they were able to switch it from on to off and transmit a data signal. Also, the light's cancellation was reversed within only a few hundred femtoseconds (one femtosecond equals one billionth of one millionth of a second) thanks to the doped POF's specific properties. 'Not only will this increase data transmission rates in POF networks, but it could be used for time division multiplexing (TDM) to increase the bandwidth of optical networks beyond what is possible with current wavelength division multiplexing (WDM) techniques,' Professor Lanzani explained. The partners said the doped POF they used for the all-optical switch was a polyfluorene called F8BT. They also succeeded in developed a number of new types of doped POF. 'In all, we developed and tested five or six new generations of materials, using different chemical agents to dope them in order to improve their optical properties and achieve very good dispersion of the doping agent in the polymer in several cases,' the project coordinator said. 'Each of the materials has different characteristics that may make them suitable for different applications.' The research sector and industry are currently assessing the use of POF for the creation of new sensing devices.