A new multiplexing scheme could allow optical networks to transmit data at petabits per second — creating enough capacity to allow two-thirds of the U.S. population to simultaneously stream HD movies over a single optical fiber. Real-time space-division multiplexed optical multiple-input-multiple-output (MIMO-SDM) was developed at Bell Labs. The technique was tested using six transmitters and six receivers in combination with real-time digital signal processing over a 60-km-long coupled-mode fiber. Where previous experiments used off-line processing, MIMO-SDM eliminated crosstalk from multiple signals using real-time processing. Implemented on a large scale, the technique has the potential to increase today's 10- to 20-Tb/s fiber capacities to the equivalent of 1000 Tb/s, according to Bell Labs. This would overcome the nonlinear Shannon limit, a theoratical limit on the information transfer rate of current optical fiber. "This experiment represents a major breakthrough in the development of future optical transport," said Marcus Weldon, president of Bell Labs and chief technology officer of its parent company, Alcatel-Lucent. "We are at the crossroads of a huge change in communications networks, with the advent of 5G wireless and cloud networking underway. Operators and enterprises alike will see their networks challenged by massive increases in traffic." The findings were presented at the IEEE Photonics Conference last month in Reston, Va. Bell Labs is the research arm of the French telecommunications company Alcatel-Lucent SA. For more information, visit www.alcatel-lucent.com.