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Hollow Core Fiber (HCF)
58 giuliomagnifico 34 5/9/2025, 1:25:17 PM holightoptic.com ↗
But a quick search proved my knowledge was not up to date - here is the paper linked from the Laser Focus World blurb someone linked above. Looks like HCFs have achieved loss parity with traditional single-mode fused silica fibers, at least in the lab. Pretty amazing and cool if you ask me!
https://eprints.soton.ac.uk/470034/1/OFC2022_PD_Jasion_submi...
From a high level, the preforms are a lot more complicated, and I imagine the draw process might be more unforgiving (in terms of size fluctuations of the cross-section), but I don't see anything that is going to be prohibitive or that will make the fiber itself 10x more expensive in the long run. Most of the cost of an undersea cable isn't in the silica anyway...
Does this mean that such fibers can be used with high-power lasers, like those used in tools and weapons?
Unfortunately we dont seems to be anywhere close to it.
[1] https://www.laserfocusworld.com/fiber-optics/article/1417001...
[2] https://news.ycombinator.com/item?id=16194973
* How do you splice without crushing the core?
* How do you terminate/splice and maintain vacuum?
* How do you terminate at all
Pressurize during the slice, and slice quickly before the pressure drops. Not hard over that very short distance.
* How do you terminate/splice and maintain vacuum?
Gas-filled, not vacuum.
* How do you terminate at all
See above.
Suggests it can be to some extent.
to enable more branching out, or both. Seen yesterday night, had a good chat with the two guys.
I always stop when I see them, to get a better picture of what is where, who owns it, and so on.
Sometimes they even let YOU do the splicing. Which is actually easy, because it's fully automated.
Imagine something like a small suitcase, or a shoebox with LCD-screen on top. You insert both ends into slits on both sides,
the 'box' grabs and aligns them, cuts and repolishes the ends, melds them together, and ejects the fibre through a slot in the front.
Then you sleeve that with tape, insert it into a muffle, apply some hardening foam, sometimes gel, like hot-glue, and close that muffle like a clam shell.
Done.
Not exactly by hand though - all the prep is done by hand but the actual alignment and fusion steps were automated by the fusion splicer machine (about the size of a small toolbox)
Would this provide for tighter channels in WDM networks (with less spacing between channels) since dispersion is less of an issue? Might be out of my league on this but I thought DCMs were a work around for dispersion at distance.
Maybe faster packets for teleprotection control systems?
Either way, cool to see!
Sticking a vacuum pump on one end and waiting presumably won't work because gas will take a really really long time to diffuse along a multi kilometer long micrometer wide tube...
Or, the entire process is performed under vacuum.
More likely, that part of the manufacturing process isn't fully solved, so they just have pumped samples.