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The design criteria is exactly the same. Have an optical medium with as little attenuation as you can. If you can't have it in a medium that is only a few meter

The design criteria is exactly the same. Have an optical medium with as little attenuation as you can. If you can't have it in a medium that is only a few meters long how could you possibly achieve it in a medium of a few kilometers? Apply your logic to copper cables. Can you have a copper cable able to deliver power over a long distance but unable to deliver the same power over a shorter distance?

quailfarmer 3y ago
The analogy doesn’t hold because one of the hardest parts of this technology is building a device that can extract the optical energy as electrical energy, and dissipate whatever heat it generates. The power density of the fiber itself is easy by comparison.
- pi-e-sigma 3y ago
  The analogy holds perfectly. Remember, we are discussing a claim that optical fiber with all required cladding/protection can carry as much power as a copper wire with all insulation having the same external dimension as the fiber cable. It is simply not possible, fiber will always have less power carrying capacity and your claim that fiber power density is 'easy' has no basis in the reality.
mlyle 3y ago
There's absolutely no reason for the application you cited to optimize diameter and isn't approaching physical limits. There's no reason you can't shove many optical fibers into that 5mm diameter. People don't, in short distance applications, to have simpler systems and connectors. There's big reasons why we don't use power over fiber (the endpoints are very expensive, and the overall system efficiencies are low). None of them have to do with the highest optical power density you could hit.
kube-system 3y ago
> The design criteria is exactly the same. Have an optical medium with as little attenuation as you can. If the design criteria for cables was "make a good cable", we wouldn't have thousands of different types. There are cables which have different mechanical and environmental properties, different cost constraints, prioritization of different performance characteristics, etc. > Can you have a copper cable able to deliver power over a long distance but unable to deliver the same power over a shorter distance? Depending on the particular application, yes. Consider some 12/2 solid Romex. It'll handle 10 watts just fine, for quite a distance, if you want. Won't work well for a 1 meter long phone charging cable, though. Different mechanical requirements.

quailfarmer 3y ago

The analogy doesn’t hold because one of the hardest parts of this technology is building a device that can extract the optical energy as electrical energy, and dissipate whatever heat it generates. The power density of the fiber itself is easy by comparison.

pi-e-sigma 3y ago
The analogy holds perfectly. Remember, we are discussing a claim that optical fiber with all required cladding/protection can carry as much power as a copper wire with all insulation having the same external dimension as the fiber cable. It is simply not possible, fiber will always have less power carrying capacity and your claim that fiber power density is 'easy' has no basis in the reality.

mlyle 3y ago

There's absolutely no reason for the application you cited to optimize diameter and isn't approaching physical limits. There's no reason you can't shove many optical fibers into that 5mm diameter. People don't, in short distance applications, to have simpler systems and connectors. There's big reasons why we don't use power over fiber (the endpoints are very expensive, and the overall system efficiencies are low). None of them have to do with the highest optical power density you could hit.

kube-system 3y ago

> The design criteria is exactly the same. Have an optical medium with as little attenuation as you can. If the design criteria for cables was "make a good cable", we wouldn't have thousands of different types. There are cables which have different mechanical and environmental properties, different cost constraints, prioritization of different performance characteristics, etc. > Can you have a copper cable able to deliver power over a long distance but unable to deliver the same power over a shorter distance? Depending on the particular application, yes. Consider some 12/2 solid Romex. It'll handle 10 watts just fine, for quite a distance, if you want. Won't work well for a 1 meter long phone charging cable, though. Different mechanical requirements.