Subsea Cables & Internet Infrastructure

As noted in my previous post, optical amplification allow light signals to be boosted without being first decoded into a digital representation. Optical-electrical-optical conversions go away. Hence the computer necessary for OEO conversions disappears. This in turn sharply improves the amplifier's reliability and life span. It also eliminates the conversion delay so end-to-end latency is improved. Finally, no computer means less cost. But these benefits are really secondary. More importantly, the advent of optical amplifiers led to a quantum leap in bandwidth that can be attributed to two related developments. The first is that optical amplifiers impose no transmission limits on computer technology. This means that we can lay a cable in the water and then upgrade it at regular intervals as Moore's law improves the ability of computers to process optical signals. Nothing on the wet side changes. Indeed, the introduction of digital processing allowed 10G wave subsea cables like ...

TAT-8 was the first Atlantic optical cable. It was RFS in 1988 and signified a bandwidth revolution with its capacity 10x that of its coaxial predecessors. By modern day standards it was a pygmy with 280 megabits total throughput. But it heralded the beginning of a long period of rapid throughput growth. Optical repeaters were spaced every 50 kilometers or 30 US miles. Photo diodes received the weak incoming signals, converted them into a digital representation of zeros and ones, and then laser diodes generated fresh light signals. A copper conductor provided power. Lots of redundancy in terms of components were built into this amplifiers to avoid repairs. However, this approach had a severe drawback, namely the throughput could not be increased in a time where Moore's law was rapidly increasing transmission rates. The pace of the optical-electrical-optical conversion was set in stone because an upgrade would require replacing all the hardware on all the amplifiers. TAT-8's ca...