AT&T Labs researchers are set to present data from a recent test that set a record for long-distance network speeds at the Optical Fiber Communication and National Fiber Optics Engineers Conference (OFC/NFOEC) on March 19.

The researchers, led by AT&T researcher Xiang Zhou, have perfected a technology that allows existing 100 gigabit-per-second fiber connections to be used to transmit over four times as much data. When used with a new low-loss optical fiber, they can sustain that data rate at distances over 7,500 miles. The new technology could dramatically increase the amount of bandwidth on the Internet's backbone, especially over submarine cables that connect the continents.

The transmission system developed by Xiang Zhou's team uses a new modulation technique that allows for the tuning of the signal to get the most out of available bandwidth. In the test data being presented next week, the researchers used a recirculating transmission test platform using 100-kilometer fiber cable segments to demonstrate that they could multiplex eight 495Gbps wave-division multiplexed signals with 100GHz of space between them over a distance over 12,000km (7,456.45 miles).

In a statement published by the organizers of OFC/NFOEC, Xiang Zhou said, "This result not only represents a reach increase by a factor of 2.5 for 100 GHz-spaced 400 G-class WDM systems, it also sets a new record for the product of spectral efficiency and distance.” A previous test by Zhou's team, using 50GHz spacing, was the previous record-holder for 400-gigabit transmission distance—at 3,000 kilometers.