Nippon Telegraph and Telephone (NTT), a Japanese telecommunications giant, just announced the development of a four-core multicore optical fiber (MCF) that delivers quadruple the capacity of conventional fiber without increasing its thickness or diameter. The company says that maintaining the cable’s cross section is crucial to ensure compatibility with existing infrastructure — not just with cable-laying vessels, but with terrestrial interconnects and terminal racks as well.
As the development of 5G communications, AI models, and cloud services accelerates across the world, so does the demand for transferring massive amounts of data. Telecommunications companies can address this demand by laying more infrastructure, but this could be a costly endeavor requiring a lot of time and resources. So, NTT instead developed the MCF, which contains four different cores (instead of the usual single core) surrounded by glass cladding. Signals are then sent through the MCF through spatial multiplexing, essentially allowing a single cable to carry four independent optical paths inside it. Since more undersea cables bundle up to 48 fibers together, NTT’s technology means that just one cable run can now carry as many as 192 cores.
The company also developed technical accessories that make it easier for cable layers and telecommunications companies to integrate the MCF into existing infrastructure. This includes the submarine joint box, which allows conventional terrestrial fiber optic cables to connect to the four-core undersea cable, and the MCF cable terminal, which is crucial for connecting it to transmission equipment that uses single-core optical cables. There is also the factory joint box that lets cable layers connect two MCF cables to each other on the seabed.
Multiple companies have been continuously laying new undersea connections despite the risks of cable cuts and regional conflicts, showing that the demand to connect the world together is steadily increasing. Meta is even said to be planning to create a new subsea cable route that avoids areas with high geopolitical tensions, such as northern Europe, the Middle East, and the Strait of Malacca.
This technology is expected to be rolled out in 2029, meaning telecom companies can start deploying it in their projects in just a few years’ time. Aside from accommodating increased traffic, the MCF could potentially reduce deployment times without the need to completely overhaul the existing system. This could make upgrades cheaper while simultaneously allowing new projects to be more competitive than existing networks.
