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sloppy_diffuser@sh.itjust.works ⁨1⁩ ⁨year⁩ ago

Its a type of fiber optic cable where the center of the cable is literally hollow. Normal fiber uses a glass core. Light passing through glass also travels about 2/3 the speed of the light since the speed of light is only constant in an empty vacuum. With hollow core, light is no longer passing through glass so its speed is much closer to the actual speed of light.

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mindbleach@sh.itjust.works ⁨1⁩ ⁨year⁩ ago
… wait, how does that work? Total internal reflection happens at the boundary to a lower index of refraction.

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- sloppy_diffuser@sh.itjust.works ⁨1⁩ ⁨year⁩ ago
  I don’t know the physics well enough, but here is some general information.
  
  en.m.wikipedia.org/wiki/Photonic-crystal_fiber
  
  www.rp-photonics.com/hollow_core_fibers.html
  
  High Group Velocity, Low Latency Signal Transmission
  
  The group velocity of guided light is usually close to the vacuum velocity of light. This implies substantially lower latency for signal transmission through hollow-core fibers.
  
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- Croquette@sh.itjust.works ⁨1⁩ ⁨year⁩ ago
  My dumb person guess is that it needs to be in a perfectly straight line.
  
  There’s probably more to it.
  
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  - sloppy_diffuser@sh.itjust.works ⁨1⁩ ⁨year⁩ ago
    Looks like it comes in spools.
    
    www.ixblue.com/store/ixf-hcf-10-100-950/
    
    I don’t know the physics of it. I posted some info for the parent you responded to. My understanding is the applied physics is different from traditional fiber.
    
    The main physical principle behind propagation of light in conventional optical fibers is total internal reflection (TIR). However, engineering of optical materials with features on the scale of the wavelength of light offers many new possibilities for manipulating light. In particular, some microstructured fibres make it possible to guide light by a mechanism different from total internal reflection. In these fibres, light is trapped in the core by an out-of-plane band-gap, which appears over a range of axial wavevectors and prevents propagation of light in the microstructured cladding [Cregan (1999)], allowing guided modes to form in the central hollow core.
    
    mpl.mpg.de/research-at-mpl/…/hollow-core-pcf
    
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Cort@lemmy.world ⁨1⁩ ⁨year⁩ ago
How do you get internal reflectance with a hollow core?

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- AffineConnection@lemmy.world ⁨1⁩ ⁨year⁩ ago
  You can’t have total internal reflection within a hollow core, but that’s not how they function.
  
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  - Cort@lemmy.world ⁨1⁩ ⁨year⁩ ago
    That’s fair.
    
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