4 ms·

I was going to do the "well akshually..." about HCFs because this article is so light on details. I used to work in a related field many years ago, and the atte

I was going to do the "well akshually..." about HCFs because this article is so light on details. I used to work in a related field many years ago, and the attenuation of these fibers relegated them to niche applications (short-lengths that needed the odd properties of a hollow core, like ultra-high power transmission, low dispersion, low nonlinearity, etc.) They were orders of magnitude too lossy for long-haul telecommunications applications at the time. 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_submitted.pdf https://eprints.soton.ac.uk/470034/1/OFC2022_PD_Jasion_submi...

pletnes 1y ago
Do the wave modes offer higher velocity?
- GlibMonkeyDeath 1y ago
  Yes, basically most of the electromagnetic wave is in the hollow (gas-filled) core, which is going to have an index closer to 1 (as opposed to ~1.4 for silica fibers.)
  - IAmBroom 1y ago
    Oh, wow! Thanks for clarifying. I get it now! (Former optical engineer, but not in fiber optics.)
chorsestudios 1y ago
A key detail I found lacking in this article was the manufacturing cost difference. It mentions that it is more expensive, but no indication of how much more expensive.
- GlibMonkeyDeath 1y ago
  A lot more expensive right now. But silica fiber manufacturing has been optimized like crazy for 50 years, so that's not a surprise. 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...
nine_k 1y ago
> ultra-high power transmission Does this mean that such fibers can be used with high-power lasers, like those used in tools and weapons?
- GlibMonkeyDeath 1y ago
  Yep, that is what funded a lot of this research early on.

pletnes 1y ago

Do the wave modes offer higher velocity?

GlibMonkeyDeath 1y ago
Yes, basically most of the electromagnetic wave is in the hollow (gas-filled) core, which is going to have an index closer to 1 (as opposed to ~1.4 for silica fibers.)
- IAmBroom 1y ago
  Oh, wow! Thanks for clarifying. I get it now! (Former optical engineer, but not in fiber optics.)

chorsestudios 1y ago

A key detail I found lacking in this article was the manufacturing cost difference. It mentions that it is more expensive, but no indication of how much more expensive.

GlibMonkeyDeath 1y ago
A lot more expensive right now. But silica fiber manufacturing has been optimized like crazy for 50 years, so that's not a surprise. 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...

nine_k 1y ago

> ultra-high power transmission Does this mean that such fibers can be used with high-power lasers, like those used in tools and weapons?

GlibMonkeyDeath 1y ago
Yep, that is what funded a lot of this research early on.