I am surprised there are repeaters involved. Is this because of the imperfections of the surface of the fibreglass tubes that cause decay of precision of the reflection over long distances(a visual noise)?
I think it's mostly that the fiber isn't a perfectly transparent medium, over tens of kilometers attenuation adds up. As said in https://news.ycombinator.com/item?id=45159639 these are just to boost power, they don't reform the signal.
Even the best optical fiber transceivers and glass are limited (practically) to about 100km; repeaters are typically placed every 60-70km. The technology for delivering power to the repeaters is fascinating. They inject 5,000-10,000VDC at one end and each repeater shunts off a tiny amount of current to power the amplifier. All of this is embedded in the cable itself before being loaded onto the cable ship.
To add more details to other replies you received, the primary factors are Rayleigh scattering and impurities absorbing light energy, at 1550nm (where this loss is least pronounced) the number that usually gets thrown around is 0.2dB/km in attenuation. That adds up to needing those repeaters at the intervals we have them.
The diagrams of the spectrum bands are wild for me (coming from the RF world) - in that world, a 2GHz channel that I'd used in some systems was considered ridiculously huge, but here in fibre the 'small' channels are 50GHz!
People really don't get the enormity of the difference - when there were policy debates in my country about rolling our new fixed line infrastructure there were literally people saying "but won't all homes and businesses just be able to use wireless in the future?"
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[ 2.2 ms ] story [ 31.8 ms ] threadPeople really don't get the enormity of the difference - when there were policy debates in my country about rolling our new fixed line infrastructure there were literally people saying "but won't all homes and businesses just be able to use wireless in the future?"
1 - https://en.wikipedia.org/wiki/MAREA
Given it's a larger market, I would have thought there would be more direct runs landing on the US coast instead of an 'intermediary' point in Canada.