NEC demos 1.15-Tbps superchannel over 10,000 km

NEC Corp. says it has successfully transmitted 1.15-Tbps over 10,000 km via optical superchannel technology. This is the first demonstration of a terabit-per-sec superchannel generated from a single laser source transmitted over such a distance, NEC asserts.

Superchannels are an emerging technology that are already finding use in announced systems (see "Infinera debuts DTN-X packet-optical transport platform with 500G PIC, OTN/MPLS support"). However, capacities of this magnitude and over this distance have not yet been implemented.

The company says its technicians transmitted four superchannels via WDM for a total capacity of 4 Tbps with a spectral efficiency of 3.6 bps/Hz. The demonstration proves the practicality of such technology for transoceanic communication links, NEC concludes.

Optical superchannels comprise phase-locked carriers with independent modulation overlapped in frequency via orthogonal frequency division multiplexing (OFDM). Superchannels provide efficient bandwidth utilization, higher spectral efficiency, and higher data rate per laser through parallelization, NEC says.

The NEC system used optical multi-tone generation, large-core/ultra low-loss fiber, intradyne digital coherent detection, and digital equalization at higher oversampling. It also took advantage of more well-established technologies such as EDFAs and DP-QPSK modulation. The experiment yielded a 2-dB system margin above the hard decision FEC threshold without using processing-intensive MAP or MLSE algorithms, NEC adds.

NEC Laboratories America, NEC's research group in Princeton, NJ, performed the demonstration. Results were published as a post-deadline paper at the recent Asia Communications and Photonics Conference (ACP 2011) in Shanghai, China.