10 Jun 2015
Beating previous 100s of meters limit, fiber now affordable for longer communications applications.Zepler Institute have successfully manufactured a record 11km of hollow core photonic bandgap fiber with low loss and a broad transmission bandwidth – a type of fibre that until now had only been made in lengths up to a few hundreds of meters. The fiber, which supports >200nm bandwidths with a longitudinally uniform loss of approximately 5dB/km at 1560nm, the key telecoms wavelength, has a 19-cell core and five cladding ring structure. It was fabricated using a conventional two-stage stack-and-draw technique.
“Hollow core photonic bandgap fiber has only had niche applications up until now because it was believed that it could not be manufactured in lengths suitable for telecoms applications,” said Dr Marco Petrovich a senior member of the Zepler Institute team developing hollow core fiber technology with funding from both the UK Engineering and Physical Sciences Research Council and the European Union's FP7 programme.
“Not only have we successfully made a photonic bandgap fibre in a suitable length, we have also engineered it to have the right properties for telecoms applications.” Petrovich and his colleagues have demonstrated that the fibre has error-free, low-latency, direct-detection 10Gbit/s transmission across the entire C-Band.
Manufacturing significantly long lengths of photonic band gap fiber is notoriously difficult because unlike conventional fibers whose properties depend on the materials used to make them, the properties of photonic bandgap fibers depend on their structure.
“Any small change in these structures can change the properties along the fiber,” said Petrovich. “We have shown that our fibre’s properties are consistent along its entire length.”
The breakthrough was made possible due to an improved understanding of fiber properties deriving from various new numerical and experimental fabrication and characterisation tools recently developed by the team of researchers.
“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 fiber,” 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.”