The largest underwater cable in the world may be capable of speeds that are 20% faster than the theoretically possible. A recent experiment with 16QAM modulation has achieved a record transfer speed of 26.2 terabytes per second on a 4000-mile transatlantic cable owned by Facebook and Microsoft. This represents a 20% improvement in 20 Tbps each pair of the eight fiber optic cables that it was originally thought to be capable of, according to the Infinera research team who conducted the test. is currently the largest underwater cable in the world with a total theoretical capacity of 160 Tbps. The cable run by Telxius moves between Bilbao in Spain and Virginia Beach, Virginia, which have since become popular sites for new data centers.
Significance of the message is double, according to Infinera. First, the new approach was demonstrated on an existing cable that potentially allows for capacity improvements without spending hundreds of millions on new wires. The second is that speed has been demonstrated on a cable that extends over such a distance.
It'll be a while before we see speeds like this that are common. Although the transfer rate of 20 Tbps was considered possible along the line, the average cable transfer rate of MAREA is only 9.5 Tbps, suggesting that there are still practical obstacles that need to be overcome.