They used 155 lasers, each operating at a different frequency and carrying 100 Gigabits of data per second, to dramatically enhance the performance of standard Wavelength Division Multiplexing (WDM) technology.
The record-breaking figure was derived by multiplying the number of lasers by their 100 Gigabit per second transmission rate and then multiplying the aggregate 15.5 Terabit per second result by the 7000 kilometer distance achieved. The combination of speed and distance expressed in bit per second.kilometers is a standard measure for high speed optical transmission.
The transmissions were accomplished over a network whose repeaters, devices used to sustain optical signal strength over long distances, were spaced 90 kilometers apart. This spacing distance is 20% greater than that commonly maintained in such networks.
The researchers also increased capacity by interfacing advanced digital signal processors with coherent detection, a new technology that makes it possible to acquire details for a greater number of properties of light than the direct detection method commonly applied in today’s systems. Using this technique the researchers were able to effectively increase capacity by increasing the number of light sources introduced into a single fiber yet still separate the light into its constituent colors when it reached its destination.
Details of the breakthrough were presented in a research paper that was reviewed in an exclusive and highly-competitive post deadline session of ECOC 2009, a prestigious European optical communications conference.
This transmission record is just the latest in a long series of Bell Labs optical networking breakthroughs that have become market-changing solutions and generated substantial growth opportunities for Alcatel-Lucent: the invention of Dense Wave Division Multiplexing (DWDM), introduction of non-zero dispersion fiber, 100 Gigabit Ethernet field trials and Differential Phase-Shift Keying (DPSK) at 40 Gigabits per second, the most widely used in 40 Gigabit per second systems worldwide.