March 24, 2006 As the world’s internet traffic grows relentlessly, faster data transmission will logically become crucial. To enable telecommunications networks to cope with the phenomenal surge in data traffic as the internet population moves past a billion users, researchers are focusing on new systems to increase data transmission rates and it’s not surprising that the world data transmission record is continually under threat. Unlike records where human physical capabilities limit new records to incremental growth, when human ingenuity is the deciding factor, extraordinary gains are possible. German and Japanese scientists recently collaborated to achieve just such a quantum leap in obliterating the world record for data transmission. By transmitting a data signal at 2.56 terabits per second over a 160-kilometer link (equivalent to 2,560,000,000,000 bits per second or the contents of 60 DVDs) the researchers bettered the old record of 1.28 terabits per second held by a Japanese group. By comparison, the fastest high-speed links currently carry data at a maximum 40 Gbit/s, or around 50 times slower.

"You transmit data at various wavelengths simultaneously in the fiber-optic networks. For organizational and economic reasons each wavelength signal is assigned a data rate as high as possible", explains Prof. Hans-Georg Weber from the Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut HHI in Berlin, who heads a project under the MultiTeraNet program funded by the Federal Ministry of Education and Research.


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A few weeks ago the scientist and his team established a new world record together with colleagues from Fujitsu. Data is transmitted in fiber-optic cables using ultrashort pulses of light and is normally encoded by switching the laser on and off. A pulse gives the binary 1, off the 0. You therefore have two light intensity states to transmit the data. The Fraunhofer researchers have now managed to squeeze more data into a single pulse by packing four, instead of the previous two, binary data states in a light pulse using phase modulation."

"Faster data rates are hugely important for tomorrow's telecommunications", explains Weber. The researcher assumes the transmission capacity on the large transoceanic traffic links will need to increase to between 50 and 100 terabits per second in ten to 20 years. "This kind of capacity will only be feasible with the new high-performance systems."

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