September 29, 2005 Murray Hill, NJ and Glasgow, Scotland -- In two papers presented to the European Conference and Exhibition on Optical Communication (ECOC) in Scotland today, Lucent Technologies'Bell Labs division announced the first reported instances of 100-Gbit/sec Ethernet-over-optical transmission. According to Lucent, the results represent a significant milestone in toward an industry migration to 100-Gbit/sec data networking.
"This work is a major first. We have broken through the ceiling in transmission rates and described two techniques that could help implement 100G Ethernet over optical systems," says Martin Zirngibl, director of Bell Labs. "With more and more enterprises moving to 10-Gbit/sec transmission, carriers are looking to implement 100-Gbit/sec Ethernet in the Metro Area Network (MAN) as a way to efficiently multiplex and transmit high amounts of data in its native Ethernet format."
According to a press release, the Bell Labs research team was able to deliver a 107 Gbit/sec optical data stream, representing 100 Gbit/sec of data transmission, plus a standard 7% overhead for error correction, using the following two technological approaches:
Duobinary Signaling: This technique uses three electrical signal levels - positive, negative and zero - to represent a binary signal for communications transmission. Duobinary signals require less bandwidth than traditional NRZ (non-return to zero) signals. The application of this bandwidth-compressing format enabled the creation of an optical 107-Gbit/sec serial data stream using a commercially available optical modulator (rated for 40 Gbit/sec).
Single-Chip Optical Equalizer: Integrated optical equalizers invented by Bell Labs researchers two years ago can compensate for transmission impairments and also for the limited modulator bandwidth in a commercially available NRZ system. NRZ is the least complex optical data format to generate. In order to demonstrate an optical 107-Gbit/sec NRZ signal, Bell Labs designed a single chip optical equalizer that compensated for almost all inter-symbol interference arising from modulator bandwidth limitations in an optical 107-Gbit/sec NRZ electronic time division multiplexing (ETDM) transmitter. As with the duobinary approach, Bell Labs researchers used a commercially available 40-Gbit/sec optical modulator in combination with the optical equalizer to generate a 107-Gbit/sec optical NRZ data stream.