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> The current is used to amplify the fibre optic signals that flow through the 1300km long cables between the peninsula and the Norwegian mainland. This is mag

> The current is used to amplify the fibre optic signals that flow through the 1300km long cables between the peninsula and the Norwegian mainland. This is magic to me. Anyone have a search term I could use to better understand how electricity is used to boost a fibre optic signal?

orlp 2y ago
The optical signal repeaters that are part of the cable every N kilometers need power to do their job.
- Waterluvian 2y ago
  Ohh there’s physical electronic repeaters. Okay. I thought this was some sort of electromagnetism witchcraft.
  - bee_rider 2y ago
    It’s all witchcraft anyway. I’m not sure what they use exactly, but even photodiodes are pure witchcraft.
  - nbernard 2y ago
    There is still some witchcraft. Look up "optical pumping amplifier" for instance.
  - cyberax 2y ago
    They actually are witchcraft. They amplify the signal directly, without transforming it into electrical signal.
deleted 2y ago
[deleted]
cricalix 2y ago
"Fiber optic amplifier undersea" should do the trick. It's not that the power supply wrapped around/alongside the fiber does anything directly; it's being delivered to amplifiers. There's a hackaday article that's got some history in it.
dekhn 2y ago
It's a optic to electronic device that is embedded in the cable, which is powered by electricity (but I think the tech was improved, see my last link). It's mentioned here: https://en.wikipedia.org/wiki/Submarine_communications_cable#Optical_telecommunications_cables https://en.wikipedia.org/wiki/Submarine_communications_cable... with more detail here https://hackaday.com/2023/08/08/under-the-sea-optical-repeaters-for-submarine-cables/ https://hackaday.com/2023/08/08/under-the-sea-optical-repeat... and pictures here: https://hackaday.com/2023/08/08/under-the-sea-optical-repeaters-for-submarine-cables/ https://hackaday.com/2023/08/08/under-the-sea-optical-repeat... (IIUC those are inside of the ship laying or repairing the fiber,a nd they normally live on the ocean floor) and tons of photos of the process of laying cable: https://www.businessinsider.com/google-facebook-giant-undersea-cables-internet-tech-2021-9 https://www.businessinsider.com/google-facebook-giant-unders... However I think there are also fully passive repeaters- https://en.wikipedia.org/wiki/Optical_amplifier https://en.wikipedia.org/wiki/Optical_amplifier
henrikeh 2y ago
I don’t know about this cable specifically, but it can be done by transferring more power to the optical signal. Erbium-doped fiber amplifiers work by utilizing a nonlinear optical effect where energy is transferred from a pump laser to the signal. This is in principle possible in any optical (glass) fiber, but by doping with exotic elements, the amplification characteristics can be optimized. Erbium is suitable for the conventional communication wavelengths. For reference I have a PhD in information theory and signal processing for fiber channels.
- pseudosavant 2y ago
  Comments like this are why I love HN!
- kaliszad 2y ago
  This is still a good practical reference I like to point out, when people ask: https://www.youtube.com/watch?v=mWqe8_5SUvk https://www.youtube.com/watch?v=mWqe8_5SUvk Richard A. Steenbergen has also other good talks, e.g. on traceroute. There are multiple versions of these talks that include more or less the same stuff with occasionally more information here and there.
- darkclouds 2y ago
  https://en.wikipedia.org/wiki/Optical_amplifier#Doped_fiber_amplifiers https://en.wikipedia.org/wiki/Optical_amplifier#Doped_fiber_... The crush to the cable could be a number of things but without knowing the terrain, and knowing these cables just lie on the sea floor, it could be caused by the cable sitting on some jagged rock and has been pulled tight elsewhere (perhaps by fisherman dredging the seabed) resulting in the cable being forced onto the jagged rock and it being crushed onto the rock. Likewise, but unlikely, some heavy object from above has some how landed on the cable, perhaps even a submarine of sorts resting on the seabed. Again knowledge of the terrain of the sea floor where the cable crush took place is key into gaining some idea of what might have happened, but I think its the first scenario, a fisherman dredging the sea floor elsewhere has caught and pulled the cable tight and the cable crush is the damage from it resting on rocks where its snagged and crushed itself from the tautness. Rock climbers and abseilers using ropes will see this with their ropes.

orlp 2y ago

The optical signal repeaters that are part of the cable every N kilometers need power to do their job.

Waterluvian 2y ago
Ohh there’s physical electronic repeaters. Okay. I thought this was some sort of electromagnetism witchcraft.
- bee_rider 2y ago
  It’s all witchcraft anyway. I’m not sure what they use exactly, but even photodiodes are pure witchcraft.
- nbernard 2y ago
  There is still some witchcraft. Look up "optical pumping amplifier" for instance.
- cyberax 2y ago
  They actually are witchcraft. They amplify the signal directly, without transforming it into electrical signal.

deleted 2y ago

[deleted]

cricalix 2y ago

"Fiber optic amplifier undersea" should do the trick. It's not that the power supply wrapped around/alongside the fiber does anything directly; it's being delivered to amplifiers. There's a hackaday article that's got some history in it.

dekhn 2y ago

It's a optic to electronic device that is embedded in the cable, which is powered by electricity (but I think the tech was improved, see my last link). It's mentioned here: https://en.wikipedia.org/wiki/Submarine_communications_cable#Optical_telecommunications_cables https://en.wikipedia.org/wiki/Submarine_communications_cable... with more detail here https://hackaday.com/2023/08/08/under-the-sea-optical-repeaters-for-submarine-cables/ https://hackaday.com/2023/08/08/under-the-sea-optical-repeat... and pictures here: https://hackaday.com/2023/08/08/under-the-sea-optical-repeaters-for-submarine-cables/ https://hackaday.com/2023/08/08/under-the-sea-optical-repeat... (IIUC those are inside of the ship laying or repairing the fiber,a nd they normally live on the ocean floor) and tons of photos of the process of laying cable: https://www.businessinsider.com/google-facebook-giant-undersea-cables-internet-tech-2021-9 https://www.businessinsider.com/google-facebook-giant-unders... However I think there are also fully passive repeaters- https://en.wikipedia.org/wiki/Optical_amplifier https://en.wikipedia.org/wiki/Optical_amplifier

henrikeh 2y ago

I don’t know about this cable specifically, but it can be done by transferring more power to the optical signal. Erbium-doped fiber amplifiers work by utilizing a nonlinear optical effect where energy is transferred from a pump laser to the signal. This is in principle possible in any optical (glass) fiber, but by doping with exotic elements, the amplification characteristics can be optimized. Erbium is suitable for the conventional communication wavelengths. For reference I have a PhD in information theory and signal processing for fiber channels.

pseudosavant 2y ago
Comments like this are why I love HN!
kaliszad 2y ago
This is still a good practical reference I like to point out, when people ask: https://www.youtube.com/watch?v=mWqe8_5SUvk https://www.youtube.com/watch?v=mWqe8_5SUvk Richard A. Steenbergen has also other good talks, e.g. on traceroute. There are multiple versions of these talks that include more or less the same stuff with occasionally more information here and there.
darkclouds 2y ago
https://en.wikipedia.org/wiki/Optical_amplifier#Doped_fiber_amplifiers https://en.wikipedia.org/wiki/Optical_amplifier#Doped_fiber_... The crush to the cable could be a number of things but without knowing the terrain, and knowing these cables just lie on the sea floor, it could be caused by the cable sitting on some jagged rock and has been pulled tight elsewhere (perhaps by fisherman dredging the seabed) resulting in the cable being forced onto the jagged rock and it being crushed onto the rock. Likewise, but unlikely, some heavy object from above has some how landed on the cable, perhaps even a submarine of sorts resting on the seabed. Again knowledge of the terrain of the sea floor where the cable crush took place is key into gaining some idea of what might have happened, but I think its the first scenario, a fisherman dredging the sea floor elsewhere has caught and pulled the cable tight and the cable crush is the damage from it resting on rocks where its snagged and crushed itself from the tautness. Rock climbers and abseilers using ropes will see this with their ropes.