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 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...