Subsea Cables & Internet Infrastructure

The new sport in Japan is breaking long haul fibre optic transmission records. NEC and the Japanese government agency, the National Institute of Communication Technology (NICT), announce new throughput records every 6 to 8 months. It is a major area of research. At the SubOptic 2025 conference NEC representatives did many presentations on their multicore research. NICT has taken a slightly different approach of combining multiple spectrum bands (C+L) with multicore fibre. This is more challenging because there are few C+L amplifier products on the market. In fact, only Subcom has manufactured and deployed such a system on the PLCN cable. Japan by the way has been a hub of innovation in optical networking and other high tech areas like space exploration. However, long term economic prospects are poor due to population decline and the low status of women which means their talents are underutilized.  What is special about this record breaking effort is the use of a 19 core fibre stran...

The great fibre optic revolution in subsea cables has two components: the fibre optic strands and the optical amplifiers. The first fibre optic subsea cable was the three fibre pair TAT-8, which connected the US to both the UK and France using a simple branching unit. But the amplifiers used computers. Hence there was no way of upgrading them to accommodate faster transmission rates. Fortunately, quantum mechanics came to the rescue. The most successful scientific theory of all times posits that adding energy to an atom will cause it to emit photons. This was one of Einstein's contributions. An American graduate student in the 80s discovered that the rare earth element erbium had special properties. If it was incorporated into glass, then a pump laser directed at the glass would raise the energy level of the erbium ions and cause them to release photons. This in itself is not that exciting. We know that any object will issue photons depending on its temperature. But if signal photo...

African carriers need to adopt the more pragmatic approach of European, North American, and Asian carriers. Virtually no carriers in these regions require customers to sign NDAs to get a price quote. It accomplishes nothing since buyers share pricing information with impunity. Nor is there need to sign the MSA and then the service order form. Again, American carriers, including competitive publicly traded carriers like Lumen, skip the NDA unless the client requests it, and even skip the MSA by putting language in the SOF that says signing it implies acceptance of the default MSA. Clearly this bureaucratic quagmire is the fault of the colonial powers that once governed Africa. They imposed their clumsy 19th century European administrative systems on the continent during the colonial period. When independent African states emerged in the 1960s, they inherited these administrative regimes. Lawyers don't understand that business is more than ris...

Each fibre strand consists of the core and the cladding. The core is like a one way road for the light to traveland cladding are the guardrails that prevent it from escaping. The refractive index measures how fast light traverses a given medium. It is defined as the ratio of the speed of light in a vacuum to the velocity of light via the medium. The core has a higher refractive index than the cladding. As long as the refractive index differential is large enough, photons that hit the cladding at a critical angle or less will bounce back into the core. Physicists call this bouncing of light internal reflection. So the core/cladding structure is designed to preserve the optical power or amplitude of the wavelengths. It minimizes optical attenuation, the great enemy of optical networking along with chromatic and polar dispersion.  The bottom middle chart shows that optical attenuation, which reflects opposing forces, reaches a minimum in the C band. The C band is defined as wavelength...

 2Africa; Senegal/Portugal; 100G; $18.5K; 2 Years. WACS; Ivory Coast/Portugal; 10G; $8,250; 3 Years. 2Africa; Nigeria/South Africa; 100G; $24,750; 1 Year. Equiano; Nigeria/South Africa; 100G; $20K; 1 Year. Equiano; Nigeria/Portugal; 100G; $19.5K; 2 Year. 2Africa; Ghana/Nigeria; 100G; $23.5K; 1 Year. 2Africa; Ivory Coast/Portugal; 10G; $10,500; 1 Year. 2Africa; Ivory Coast/Portugal; 100G; $33.5K; 3 Year. Remarks: 2Africa CLS cross connects are $150 max. WACS cross connect charges are five digit.

Part 1 finished by noting that that the CLS in most cable systems has been downgraded to a building housing just the power feed equipment. This reflects the open cable model where each owner has fibre pairs or spectrum as opposed to a cut of the cable't lit capacity. A good example is 2Africa in Senegal. Most of the SLTEs (subsea line termination equipment) are collocated in the carrier neutral ONIX facility. But Facebook decided to put its SLTE in one of three N Plus data centers.  Another important element is the branching unit, which originally just took the main trunk's fibre pair and allocated them into two small trunks. TAT8, the first fibre optic cable, used a branching unit to land one fibre pair in the UK and the other in France. Branching units have evolved over time and most today have the ability to switch wavelengths and more recently fibre pairs. The advantages include being able to reroute traffic in case one branch fails. The branches are typically buried on the...