Tuesday, March 27, 2007

Alcatel-Lucent Carries 25.6 Tbps over Single Fiber

Researchers at Alcatel-Lucent have transmitted a world record 25.6 Terabits per second (Tbps) of optical data over a single fiber strand, using 160 WDM channels. This surpasses the previous transmission record of 14 Tbps, established in September 2006.

The experimental system transmitted 25.6 Tbps of data through three 80-km spans. The data used wavelength division multiplexing in both the C (conventional) and L (long) wavelength bands and, to double the total capacity, polarization multiplexing in each wavelength was employed. Distributed Raman amplification was used to increase the received optical signal-to-noise ratio and to allow the use of a single dispersion-compensating fiber for both bands after each span.

Maximizing spectral efficiency, which is the amount of information that can be transmitted within a unit bandwidth, was also critical to realizing this world record. In this experiment Alcatel-Lucent's Bell Labs researchers in New Jersey and Alcatel-Lucent's Research and Innovation researchers in France used an advanced signalling format called RZ-DQPSK (return to zero differential quadrature phase-shift keyed) to realize a record-breaking 3.2 bits/second/Hertz (b/s/Hz) of spectral efficiency. This is a significant improvement over today's commercial systems that generally operate at spectral efficiencies of between 0.2 and 0.4 b/s/Hz.

Also involved in this experiment were scientists from the National Institute of Information and Communications Technologies in Tokyo (NTIICT), and also from Sumitomo Osaka Cement in Chiba, Japan.


See also