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NEC has broken the ultra-long haul internet speed record by transmitting 1.15 terabits per second with a single laser over a distance of 10,000km (6,213 miles). In total, four lasers were used simultaneously to transmit 4Tbps down a single optic fiber.
Unfortunately NEC’s press release is light on details, but it seems like the engineers used fairly standard tech to achieve this new speed record. Each laser encodes its data using orthogonal frequency-division multiplexing (OFDM) superchannels (the same technique used by DSL, WiFi, and more), and then four of these “superchannels” are multiplexed into a single cable using wavelength division multiplexing (WDM — the same technique currently used to squeeze multiple optical channels down a single fiber). We’re not entirely sure, but the novel innovation here is probably the use of OFDM with optical signals. The work was carried out by NEC’s research group in Princeton, New Jersey, which is close to the landing point of numerous transatlantic cables.
Faster speeds have been transmitted over fiber in recent years, but only over very short distances — and short distances aren’t really a problem, as far as the internet goes. The significance here is the distance of NEC’s transmission speed record: 10,000km is long enough to span the Atlantic or Pacific. Submarine cables are incredibly expensive and difficult to lay, and really, where possible, you want to make the most of existing infrastructure instead of laying a new cable — which is exactly what NEC’s technology promises to do.
The current state-of-the-art for transoceanic connectivity is between 10 and 100Gbps per optical fiber. The fattest cable in the world, the TGN-P which spans the Pacific between Japan and the USA, currently maxes out at around 7Tbps, which means it has around 150 “lit” fibers. The key behind NEC’s discovery is that it can be used on existing fiber optic networks — and so in this case, if the routers on either end of TGN-P were upgraded with NEC’s technology, the cable’s total capacity would jump from 7Tbps to 150Tbps or more.
Read more at NEC (press release)