This is really cool! Existing DNANF cables have crazy low latency, but have too much signal loss to be used outside of datacenters basically.
The DNANF design solves this by using concentric glass tubes that are just microns thick. These act like tiny mirrors, bouncing the light back into the air core and suppressing higher-order modes. Testing this on 15km spools using multiple measurement methods, including optical time-domain reflectometry, confirmed attenuation under 0.1 dB/km.
Seems like this new design solves that problem, which might mean these could be used over longer distances. This could significantly reduce latency of the internet as a whole.
Now to fix the stranglehold ISPs have on (esp American) infrastructure…
How does lower loss improve latency?
Lower loss in general means fewer repeaters, and repeaters always add latency.
For this cable specifically, the optical signal spends significant time traveling through air, which has a lower index of refraction (higher signal speed) than the solid-glass cables in common use.
The article abstract claims a 45% improvement in signal speed, which would reduce latency over longer distances simply because the information arrives sooner.
Thank you.
As far as I understand, the latency is improved by the different speed of light of the DNANF: In conventional fibres, it is limited by the refractive index of glass, reducing the speed of light in it to ~70% of speed of light in vaccum (Wikipedia on this topic). In this new concept, the light travels 45% faster.
I think, the lower loss (lower attenuation) is “just” an enabler for long distances: You can easily have hundreds of km without repeaters – and repeaters for DNANF cables would add latency. If they can get attenuation improved a bit more, they may even be able to cross the Atlantic ocean without repeaters.
As a nice side effect, those DNANF cables have very little dispersion, so you can get rid of compensating for that, which will reduce latency too.
