To meet international bandwidth demand that is nearly doubling every two years, Japanese companies NEC and NTT have successfully piloted a revolutionary submarine cable technology that will dramatically improve internet speeds under the sea.
The transoceanic-class experiment transmitted hundreds of terabits over a staggering distance of 7,280 km, a feat made possible by a sophisticated algorithm.
NEC and NTT’s innovative solution uses a 12-core multicore fiber, consisting of 12 optical signal transmission paths within a standard outer diameter optical fiber, a significant improvement over existing single-core fiber used in submarine cables.
MIMO technology
However, adding more cores to an optical fiber comes with its own challenges. Interference or crosstalk occurs when optical signals leak from one core to another, leading to a degradation in communication quality. This is amplified in long-distance transmission, where the non-uniformity of delay and loss between signals makes accurate reception difficult.
To overcome these problems, NEC has developed an algorithm for demodulating received signals using MIMO technology. This allowed accurate separation and demodulation of received high-speed signals. At the same time, NTT developed the interconnected 12-core multicore fiber optic transmission line that mitigates the effects of non-uniformity in signal delay and loss.
NEC and NTT say they want to commercialize their research in the future, which could potentially contribute to the realization of an optical submarine cable system and a high-capacity terrestrial core network.
The research team, which recently presented its findings as a high-profile paper at the OFC 2024 Technical Conference in San Diego, estimates that such systems could operate at hundreds of terabits per second depending on specific cable designs, potentially heralding the arrival of petabit . per second class of submarine cables.