Bell Labs pushes optical Ethernet to 100 Gb/s

In two papers presented to the European Conference and Exhibition on Optical Communication (ECOC) in Scotland today, researchers at Bell Labs, a division of Lucent Technologies, reported conducting transmissions of 100 Gb/s Ethernet over fiber, claiming to be the first in the industry to achieve such speed with optical Ethernet.

Using two methods--“duo-binary signaling” and a single-chip optical equalizer--the researchers delivered a 107 Gb/s optical data stream over 1.8 km: 100 Gb/s of data transmission plus 7% overhead for error correction. Duo-binary signaling, which requires less bandwidth than traditional signals, uses three electrical signal levels--positive, negative and zero--to represent a binary signal. The other approach used a simpler, traditional signal and employed an equalizer invented by Bell Labs that compensated for interference created by the transmitter’s bandwidth constraints.

For both approaches, researchers bonded commercially available “off the shelf” 40 Gb/s transceivers to reach triple-digit speeds. But there was no equivalent equipment on the receiving end, just “a bunch of meters in a lab,” a Bell Labs spokesperson said.

Using the Bell Labs equalizer, the team achieved an optical signal-to-noise ratio of 21 dB and a bit error ratio of 0.01.

The group also used fiber without dispersion compensation. With special dispersion fiber, the spokesperson said, the solution these researchers used to span less than 2 km could likely transmit across several thousand kilometers.

Though commercial availability of the capabilities the researchers reported will take some time, the group imagines demand for the technology in metro area networks.

“With Ethernet line rates historically jumping by factors of 10, we expect 100 Gb/s Ethernet to be required relatively soon,” the researchers wrote.