[Wonder Warthog]

"Don’t the fiber optic cables have signal boosters every so often? Then any potential eavesdropper would have electrical energy to deal with instead of light."

Good question. Best I can say is "maybe". Signal boosters modulate a semiconductor laser chip, so there is still no direct access to the signal. "Probably" any signal booster is boosting multiple cables with multiple laser chips simultaneously , so any radiated EMF is probably a mish-mash of different "conversations" from all the cables.

[mad_as_he$$]

I notice that land based fiber cables have a “booster” station at regular intervals on their route. Seems logical deep sea would have them also.