Researchers from the National Institute of Information and Communications Technology (NICT, President: TOKUDA Hideyuki, Ph.D.), Network Research Institute, succeeded the first S, C and L-bands transmission over long-haul distances in a 4-core optical fiber with standard outer diameter (0.125 mm). The researchers, lead by Benjamin J. Puttnam, constructed a transmission system that makes full use of wavelength division multiplexing technology by combining different amplifier technologies, to achieve a transmission demonstration with date-rate of 319 terabits per second, over a distance of 3,001 km. Using a common comparison metric of optical fiber transmission the data-rate and distance produce of 957 petabits per second x km, is a world record for optical fibers with standard outer diameter.

In this demonstration, in addition to the C and L-bands, typically used for high-data-rate, long-haul transmission, we utilize the transmission bandwidth of the S-band, which has not yet been used for further than single span transmission. The combined 120nm transmission bandwidth allowed 552 wavelength-division multiplexed channels by adopting 2 kinds of doped-fiber amplifier together with distributed Raman amplification, to enable recirculating transmission of the wideband signal. The standard cladding diameter, 4-core optical fiber can be cabled with existing equipment, and it is hoped that such fibers can enable practical high data-rate transmission in the near-term, contributing to the realization of the backbone communications system, necessary for the spread of new communication services Beyond 5G.

The results of this experiment were accepted as a post-deadline paper presentation at the International Conference on Optical Fiber Communications (OFC 2021).