Fiber optics of the future may be manufactured in space if the results of a recent ISS experiment prove its feasibility.

After a month-long trial run of equipment produced by space manufacturing startup Flawless Photonics, NASA said it was able to make more than seven miles (11.9 km) of ZBLAN optical fibers with a presumptive level of quality that'll make them a far superior product to typical silica-based fibers.

The University of Adelaide's Institute for Photonics and Advanced Sensing (IPAS), a research partner on the project and supplier of 20 rods of ZBLAN used to create the space fibers, said the results were "a remarkable achievement" considering previous efforts only elicited fibers in the range of 20 meters in length.

According to NASA, seven of the draws exceeded 700 meters, with the longest reaching more than a kilometer. 

The project "demonstrat[ed] for the first time that commercial lengths of fiber can be produced in space," NASA said.

ZBLAN is a heavy metal fluoride glass alloy consisting of various mixtures of zirconium, barium, lanthanum, sodium and aluminum fluorides. It's a great material for fiber optic cables, and has long been used for such, but it's never been as successful as plain old silica glass because of a couple of serious issues.

"Gravity causes ZBLAN to crystallize during the drawing process, and second, the purity of the glass must be enhanced by a factor of 1,000 for it to fulfill its maximum potential," said IPAS deputy director and professor Heike Ebendorff-Heidepriem. Terrestrially manufactured ZBLAN fibers are also notoriously brittle.

The professor's team was responsible for manufacturing ultra-pure ZBLAN preforms to be drawn into fiber in space, while Flawless Photonics designed the manufacturing hardware flown to the ISS in January. 

If everything in the manufacturing process went according to plan, the resulting fibers should be hardy and free of crystals. Put into use, the space-made ZBLAN fibers should have ten times the capacity of silica-based fibers.

Flawless Photonics founder and CEO Rob Loughan told The Register the fibers should be back on land sometime soon, after which they'll be tested and sold to companies wishing to experiment with the next generation of ZBLAN.

Loughan told us that they've already filled several orders for fibers priced at $1,000 a meter (which we're told is also the going rate for terrestrially manufactured ZBLAN fibers). Loughan said the company had recently taken an order for $100,000 worth of the fibers, which works out to around 100 meters.

Step 2: Make more fiber in space

Interest seems to be there, and there's more than 11 kilometers of ZBLAN fiber set to return to Earth from the ISS - great. How are we going to get more of the stuff?

Loughan told us that, with considerable interest being shown, Flawless Photonics is already planning what to do next. 

While he wouldn't name names, Loughan said Flawless is working with an orbital manufacturing partner (there are several such endeavors to establish a permanent private industry presence in space) and plans to have several of its manufacturing machines in orbit by mid year. 

NASA has given Flawless permission to send manufacturing machines back to the ISS, so even if the private launches are delayed, there will still be limited ISS manufacturing space to be had.

Along with plans to manufacture more ZBLAN fiber in space, Flawless is also working on developing purification technology so it can make its own ZBLAN preforms in orbit as well. A future test will see space-made preforms sent back to Earth for fiber pulling to see whether the reverse of the current project yields any improvements. 

"Our moonshot is eventually pulling thousands of kilometers per run. We want to replace subsea cables," Loughan told us. There's still plenty of work to be done to get there, but the results thus far suggest one hurdle has been jumped. ®

https://www.theregister.com//2024/04/23/miles_of_fiber_optic_lines/