Alca-Lu clocks 300 Gbps over 10,000 km submarine cable

Get ready for more confusion about optical fibre speed and distance records: Alcatel-Lucent has announced a 300 Gbps, 10,000 km transmission on a submarine cable test-bed.

The announcement, here, touts the test of a 300 Gbps modulation technology over 10,000 km using “second-generation coherent submarine” fibre.

What's being shown off here is new kit for the ends of the fibres: a platform, Aca-Lu Submarine Networks' 1620 SOFTNODE, which uses 8QAM (8 quadrature amplitude modulation) to drop the signal on the fibre.

QAM combines the phase of a signal with amplitude to increase the number of bits a given bandwidth can carry. Ultimately, the company expects 8QAM to let submarine cables carry 15 Tbps per fibre pair, “equivalent to 2.25 million HDTV channels streamed simultaneously”.

Using El Reg's 100 MB blue-movie unit of measurement, 15 Tbps would deliver 18,750 grumble flicks per second.

Optical fibre records are a competitive and frequently confusing: Alcatel-Lucent's 10,000 km run is only a little shy of the 12,000 km claimed by UCSD boffins at the end of June.

However, Alcatel-Lucent is pitching its record as something cable owners can buy, while UCSD was offering a new way to handle distortion (and presumably, when commercialised, send signals even further).

Huawei claimed a speed record this year – 1 Tbps over 1,000 km – while Alcatel-Lucent had alread reached 1.4 Tbps (albeit over a paltry 410 km).

Last year, Danish boffins hit an impressive 43 Tbps – but their work needs new multi-core fibres that aren't going to replace the glass already sitting on the bottom of the ocean, any time soon. ®