The transmission, which reportedly involved what ZTE called “a unique frequency algorithm,” used a WDM system based on 100-GHz channel spacing. The link included 25 ROADM nodes, but no electrical repeaters. The company did not reveal where the trial took place, whether a carrier was involved, and whether the optical transport system used was a prototype or commercially available.
Related: First successful North American 400G field trial conducted
More: CDFP MSA group forms to advance 400G cabling, modules
The trial is the most recent in a series of 400-Gbps experiments ZTE has conducted. The company reported at the ECOC 2012 tradeshow that it had sent 40 channels, each running at 400-Gbps, over 2800 km of standard singlemode fiber. The company also unveiled a 400-Gbps/1-Tbps prototype optical transport system the previous June. ZTE said the 5000 km set "a benchmark for the global optical networking industry."
However, as noted by Lightwave, AT&T delivered a paper at this year's OFC/NFOEC in which it reported transmitting 400 Gbps over 12,000 km using a time-domain-hybrid modulation format that comprised a mix of 48 QPSK and 77 8QAM symbols on a 100-GHz grid.
See: Looking from 100/400G toward Terabit networking line cards