The internet keeps growing but how to cut its energy use? A new record for the speed at which a single laser can transmit data could help solve this problem.
and colleagues at the Karlsruhe Institute of Technology in Germany sent data at a rate of 26 terabits per second through 50 kilometres of optical fibre. That鈥檚 equivalent to sending all the information on 1000 HD DVDs each second.
Previously, higher transmission speeds have relied on multiple lasers. But being able to use just one is far more energy efficient. 鈥淔or each laser you need a separate power supply,鈥� explains team member .
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, a green IT consultant based in Ottawa, Canada, agrees that the new result is a step in the right direction. 鈥淣ot only do you have higher maintenance costs, with each laser there is a whole bunch of associated equipment such as filters, regenerators and so on,鈥� he says.
Divide and conquer
The amount of data that a laser can carry depends on dividing the beam into separate colours or lines, each of which acts like a separate data carrier. These in turn can be split into further channels by altering their polarisation, amplitude and phase. However, this additional 鈥渕odulation鈥� causes the lines to overlap so to retrieve the data they have to be disentangled with a 鈥渇ilter鈥� at the end.
The previous record for a single laser was 10 terabits per second. This time around, the researchers managed to divide their laser into even more lines and improve the technique they use to disentangle them afterwards, says Freude. Crucially, they were able to do the filtering using an optical, rather than electronic, processor, which is faster.
Such blistering speeds are not required by single home internet connections. The obvious application is for 鈥渓ong haul鈥� traffic through the internet鈥檚 backbone. Some predictions say that by 2018, these transmissions could use up to one-fifth of the world鈥檚 energy.
鈥淣o one could afford that,鈥� says Freude, so smarter ways to deal with such high-speed data streams are urgently needed.
Journal reference: Nature Photonics, DOI: 10.1038/NPHOTON.2011.74
