Subsea Cables & Internet Infrastructure

Hollow core enjoys 33% lower latency than standard solid core single mode fibre. Moreover, it offers at least 50% more bandwidth because a much wider spectrum band can be used. In contrast, solid glass is hobbled by high attenuation outside the C and L bands. A final advantage is hollow core exhibits little chromatic dispersion. Single mode fibre is bedeviled by polar mode and chromatic dispersion. In each case, the speed of light through glass varies sufficiently by wavelength to blur the signal by the time it reaches the far end. The coherent optics revolution was largely about using digital signal processing to unscramble the signal or more precisely to use physics to work backwards and infer the original, pristine signal. But hollow core technology until now has been stymied by very high optical attenuation. This simply means the light fades rapidly as it passes through the hollow core. The light is absorbed rapidly by the surrounding glass border due to the absence of refraction. ...

The O band was the original or first official spectrum range in optical fibre optic communications. It includes the wavelengths ranging from 1260 nm to 1360 nm. The first fibre optic cable trials and deployments in the mid-70s were very short range ranging from a few metres to several kilometres. In 1977 the first phone voice traffic traversed a local fibre optic link in Long Beach, California. The Dorset, UK police deployed a fibre optic link in 1975, but unfortunately, I have been unable to ascertain the specific application. NORAD used fibre optic cables to connect computers at its underground Cheyenne Mountain headquarters in 1975. Note that this 1970 experiments used 850 nanometers as the semiconductor lasers were not capable of longer wavelengths. The O band became the de facto standard in the early 80s when the industry migrated from the early multimode fibres to single mode fibres and gallium arsenic enables lasers to to achieve the longer wavelengths of the O band. By 1988 com...

The Japanese National Institute of Information and Communication set a single fibre pair transmission record of 22.9 petabits last November. To achieve it, multicore was combined with multiple frequency bands including the standard C-band, L-band (in limited production use today), and S-band. The C-band is the work horse of optical infrared transmission with a wavelength range of 1530-1550 nanometers. These wavelengths experience the least attenuation in a glass medium; they are also ideal for erbium-doped optical amplifiers. The L-band includes the 1565 to 1625 nanometer range. Its attenuation in glass is the second lowest. Arelion has used L-band in its US East Coast network. At least one Pacific cable has used L-band as well. I believe it is PLNC which connects HK to the US. The S-band ranges from 1460 to 1515 nanometers. The 'S' stands for short band. It has the third lowest attenuation in glass. The Japanese combined these three bands with a 38 core fibre strand which they...