Bell Labs reported transmissions of 100 Gbps Ethernet over optical. These results are a significant milestone in the industry’s march towards migrating to 100 Gbps data networking.
The Bell Labs research team was able to deliver a 107 Gbps optical data stream, representing 100 Gbps 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-Gbps serial data stream using a commercially available optical modulator (rated for 40 Gbps).
- 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-Gb/s 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 Gb/s NRZ electronic time division multiplexing (ETDM) transmitter. As with the duobinary approach, Bell Labs researchers used a commercially available 40-Gbps optical modulator in combination with the optical equalizer to generate a 107-Gbps optical NRZ data stream.
Lucent Technologies presented papers on both of these approaches at to the European Conference and Exhibition on Optical Communication (ECOC) in Scotland.
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