REFINED FIBRES
Refined fibres drive optical networks to new heights
Specialised fibres, whether multicore, or doped for specialised performance are supporting higher transmission rates and more energy- efficient networks. Matthew Peach reports.
full commercial or academic collaboration with us,” said Professor Sir David Payne, Director of the ORC. “But we wanted to enable any organisation to get hold of small quantities of a fibre that the ORC has already made or can easily make. “As the ORC can now routinely make fibre that far exceeds the capabilities of other commercially-available fibres, the new ORC service gives external organisations access to usable samples of these specialised fibres quickly and easily.” Sumitomo develops new multi-core optical fiber Sumitomo Electric Industries has developed a multi-core optical fiber including eight cores in the standard 125µm cladding suitable for optical interconnects, and realized an ultra-high-density fiber optic cable with the highest core density ever reported. To cope with the growing data traffic in the short-reach interconnects used for parallel processing in supercomputers and resource disaggregation in data centers, optical interconnect technologies for broadband high-density transmission are intensively researched and developed. At the same time, the multi-core optical fiber (MCF), which has multiple cores in one fiber, has been also intensively researched and developed. Sumitomo’s MCF is expected as a next-generation optical fiber that will enable ultra-high- capacity transmission systems. Most of the previously-reported MCF developments permitted the cladding diameter to be thicker than the standard 125µm diameter fibers to increase core count while achieving optimal
ORC’s breakthrough was made possible due to an improved understanding of fibre properties deriving from various new numerical and experimental fabrication and characterisation tools recently developed by Petrovich’s team. “We demonstrated data transmission at 10Gb/s along a 11km span using direct detection, showing only minor penalties and achieving an estimated >15μs latency reduction relative to standard fibre,” said Petrovich. “Our numerical models of the fibre drawing process give us confidence that much longer fibre yields are feasible through further scaling of the process, and that much lower loss fibres should ultimately be possible.” Next-generation optical fibre now available Besides the new hollow core photonic bandgap fibre development, the Optoelectronics Research Centre announced that it is making its specialized, next-generation fibre available for general purchase. Fibres available for sampling and to purchase include rare-earth- doped fibres with ultra-high dopant concentrations; large mode area fibres; high bend radius fibres; multi-trench fibres; and novel compositions with extreme aluminium or germanium concentrations. The service will enable the evaluation of ORC fibres in products and research programmes at the earliest stages of development, helping to accelerate performance, adoption and commercialisation of optical fibre and photonics- based products. “Until this development, the only way to get fibre from the ORC has been as part of a
Dr Marco Petrovich, a senior member of the ORC fibre development team, said, “Hollow core photonic bandgap fibre has only had niche applications up until this achievement because it could not be manufactured in lengths suitable for telecoms applications. Not only have we successfully made a photonic bandgap fibre in a telecoms-suitable length, we have also engineered it to have appropriate properties for telecoms applications.” Petrovich and his colleagues have already demonstrated that the fibre has error-free, low-latency, direct-detection 10Gbit/s transmission across the entire C-Band, which is used for long-distance telecommunications. “We have shown that our fibre’s properties are consistent along its entire length.”
Matthew Peach
R esearchers at have manufactured a record 11km of hollow core photonic bandgap fibre, a special optical fibre that until now had only been possible in lengths of some hundreds of meters. The fibre, which supports >200nm bandwidth with a longitudinally uniform loss of approximately 5dB/km at 1560nm, has a 19 cell core and five cladding ring structure. It was fabricated using a conventional two-stage stack-and-draw technique. Southampton’s Optoelectronics Research Centre
Cut-away of a hollow core photonic bandgap fiber is shown neck down, as generated by a fluid dynamics simulation. The approximately 10mm-wide preform is drawn down to a slender approximately 0.2mm fiber in a hot furnace under gravity and longitudinal tension. The outer glass is coloured to show temperature (hottest region in white), while the microstructure is colored to show whether surface tension (blue) or differential pressure (red) forces dominate. Image supplied by University of Southampton.
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ISSUE 5 | Q3 2015
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