An attempt to optimise optical fibre capabilities has led a team including a Silicon Valley start-up and scientists from Adelaide University to undertake some space manufacturing – with immediate success.
Fibre optic communication converts an electrical signal into a pulse of light sent through a cable – usually a thin silica or glass tube. Converting the pulse back to an electrical signal provides usable data. This optical cable reflects the light within the cable, maximising the signal transferred over long distances compared to copper wires. It is the backbone of global internet, telecommunication networks and so much more.
But manufacturing fibre optic cable to its highest quality on earth presents problem due to gravity.
Current manufacturing involves a draw tower, which lets melted glass fall towards the ground under the effect of gravity. As molten glass descends to the ground, the glass narrows to its intended diameter.
To overcome the problems caused by gravity, The University of Adelaide’s Institute for Photonics and Advanced Sensing (IPAS) Optofab team sent glass rods into space. On January 31st, the glass rods and a fibre production device were delivered by a SpaceX rocket into orbit and installed on the ISS.
The results were impressive: it produced more than 8km of continuous optical fibre in just two weeks of run-time. The production rate is a vast improvement on current capabilities on Earth.
ZBLAN glass was used because of its incredible performance compared to commercial-grade silica.
It has a broader transmission range, allowing signals to be sent over longer distances before experiencing attenuation and it has greater bandwidth along the fibre to send more data in a shorter time.
Transferring more data over an extended range reduces the need for power amplification to send signals across the globe.
The future of space manufacturing
But Professor Heike Ebendorff-Heidepriem says for a ZBLAN fibre to deliver on its potential there are two obstacles that must be overcome.
“First, gravity causes the ZBLAN to crystallise during the drawing process, and second, the purity of the glass must be enhanced by a factor of 1000 for it to fulfil its maximum potential.”
The professor and her team are currently working on the second challenge, but the first challenge required some outside help.
Space fibre optic start-up Flawless Photonics developed a fibre drawing device that can extrude the ZBLAN glass in space to create the fibre under the microgravity of planetary orbit.
Design of optical fibre drawing device used in space for fibre production.
The optical fibre is to be brought back to Earth for the IPAS team to analyse, characterise and determine the optical properties of this space-made fibre, to confirm or debunk its theoretical improvement over earth-made counterparts.
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