Xtera Communications, Inc. has reported the results of a recent demonstration of 100-Gbps coherent transmission paired with Raman amplification technologies. The demonstration consisted of 26 channels at 100-Gbps each with coherent detection, including digital signal processing and soft-decision forward error correction.
The channels traveled over a 424-km long unrepeatered link with optical attenuation of 74.2 dB. This result exceeds the unrepeatered transmission of 8x100G over a loss in excess of 76 dB previously reported by Xtera.
The demonstration underscores the potential of coherent 100-Gbps transmission when used with Raman amplification, Xtera asserts. The company also points out this technology pairing in other link configurations, including:
- Up to 3,000-km unregenerated transmission distance with uniformly spaced in-line amplifiers
- Insertion of long spans within an all-optical path (e.g., 250-km, 60-dB span in an all-optical route exceeding 1,300 km already deployed by Xtera in an Nx100G network)
- An all-optical path of 2,400 km engineered and deployed by Xtera in an Nx100G network.
Xtera says that the noise performance of Raman amplification combined with the higher coding gain provided by soft-decision forward error correction can ensure longer reach and better performance than competing technologies. Raman optical amplification also enables precise and optimum control of the per-channel profile, which limits nonlinear effects to extend reach even further, according to the company.
"Beyond unrivalled reach performance, Raman optical amplification offers wide optical bandwidth that cannot be matched by traditional transmission systems based on Erbium-Doped Fiber Amplifier (EDFA)," said Herve Fevrier, executive vice president and COO at Xtera Communications. "As a result, using our high-performance common line equipment and our current 100G technology, Xtera can offer 15-Tbps line capacity today."
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