That's a great article ... I was heavily involved with terrestrial fiber systems in the '90s and, while speeds and the isolation of DWDM channels have both impr

That's a great article ... I was heavily involved with terrestrial fiber systems in the '90s and, while speeds and the isolation of DWDM channels have both improved, it's amazing to me how familiar it all feels. When they talk about sub-sea amplifiers (and many of the terrestrial ones), they're not talking about a device that amplifies the signal electronically. An Erbium-Doped Fiber Amplifier (EDFA) uses a laser to optically amplify a signal. This is why there's not a lot of latency added in the sub-sea cable. If you take the same optical signal, convert it to electrons, amplify it and convert it back to an optical signal you'll see the latency added as discussed in the article. One small nit ... dark fiber represents unused capacity. There are several places where the article says something like "dark fibre signals" which is incorrect. Dark fiber has no signal, while lit fiber does. The last thing I'll mention is that these systems are obviously single-mode fiber. The laser powers feeding each channel are probably around 12dBm in the 1550nm spectrum (per channel). If you look into the end of one of these fibers that's lit from the other end, you'll end up with burned spots on your retina. Wiggle it around a bit and you'll have squiggle shaped burns. So if you're ever around fiber equipment, don't look directly at the ends (or into the connectors). You can get laser safety glasses cheaply ... save your sight!