Optical transmission systems with Terabits per second single-channel line rates no longer seem to be too far-fetched. New services such as cloud computing, three-dimensional high-definition television and virtual-reality applications require unprecedented optical channel bandwidths. These high-capacity optical channels, however, are fed from lower-bitrate signals. The question then is whether the lower-bitrate tributary information can viably, energy-efficiently and effortlessly be encoded to and extracted from terabit per second data streams. We demonstrate an optical fast Fourier transform scheme that provides the necessary computing power to encode lower-bitrate tributaries into 10.8 and 26.0 Tbps line-rate orthogonal frequency-division multiplexing (OFDM) data streams and to decode them from fibre-transmitted OFDM data streams. Experiments show the feasibility and ease of handling terabit per second data with low energy consumption. To the best of our knowledge, this is the largest line rate ever encoded onto a single light source.

Scientists at Karlsruhe Institute of Technology (KIT) have succeeded in encoding data at a rate of 26 terabits per second on a single laser beam, transmitting the data over a long distance of 50 kilometers, and decoding the information successfully. This is the largest data volume ever transported on a laser beam. The process developed by KIT enables the transmission of 700 DVDs’ worth of content in just one second.

In this experiment, KIT scientists led by Professor Jürg Leuthold applies the so-called orthogonal frequency division multiplexing (OFDM) for record data encoding. For many years, this process has been used successfully in mobile communications, based on mathematical routines (Fast Fourier Transformation). According to Leuthold, transmission of 26 terabits per second confirms that even high data rates can be handled today, while energy consumption is minimized.

Video transmissions consume much Internet bandwidth and require extremely high bit rates. The need is growing constantly. In communication networks, first lines with channel data rates of 100 gigabits per second (corresponding to 0.1 terabit per second) have already been taken into operation. Research now concentrates on developing systems for transmission lines in the range of 400 Gigabits/s to 1 Tbit/s. Hence, the Karlsruhe invention is ahead of the ongoing development with their 26 Terabits per second laser data transmission.