NEC breaks spectral efficiency record over single optical fiber, close to Shannon limit

NEC Corporation (Tokyo) this week announced that it has demonstrated a transmission capacity of 34.9 terabits per second (Tbit/s) on a single optical fiber, over a distance greater than 6,300 km. This achievement breaks the spectral efficiency record for transoceanic transmission (*), achieving 8.3 bit/s/Hz using the C-band spectrum. This is a 16.9% improvement on the previous record, contends the company.

"These results come very close to the Shannon limit, the fundamental spectral efficiency limit of optical communications," said an NEC press release. "Maximizing spectral efficiency is one of the primary goals in the design of submarine cable networks, enabling the highest possible capacity per fiber pair, while reducing the terminal equipment cost, space and energy consumption. This demonstration of NEC’s technologies comes within 0.5 decibels (dB) of the theoretical maximum value."

"We are proud to have come so close to Shannon's cornerstone of communication theory," said Toru Kawauchi, general manager of the Submarine Network Division at NEC Corporation. "NEC's research and development teams will continue to explore the limits of even greater subsea capacity, flexibility, and cost-effectiveness."

The research results were recently presented at the post-deadline session of the Optical Fiber Communication Conference and Exhibition (OFC) 2016 in Anaheim, California.

(*) According to research by NEC. The previous world record was 7.1 bit/s/Hz.