NEC breaks world record for spectral efficiency, close to Shannon limit

NEC has demonstrated a transmission capacity of 34.9 terabits per second (Tbit/s) on a single optical fiber, over a distance greater than 6,300 km. This achievement breaks the spectral efficiency record for transoceanic transmission, achieving 8.3 bit/s/Hz using the C-band spectrum. This is a 16.9% improvement on the previous record. These results come very close to the Shannon limit, the fundamental spectral efficiency limit of optical communications.

Maximizing spectral efficiency is one of the primary goals in the design of submarine cable networks, enabling the highest possible capacity per fiber pair, while reducing the terminal equipment cost, space and energy consumption. This demonstration of NEC’s technologies comes within 0.5 decibels (dB) of the theoretical maximum value.