[Update: Live] Google Dunant trans-Atlantic cable marks first use of SDM tech for record-breaking capacity

Google in 2018 announced two private intercontinental undersea cables; becoming the first major non-telecom company to build its own after years of leasing or consortiums. The second, named Dunant, will feature record-breaking capacity by being the first cable to leverage space-division multiplexing (SDM) technology.

Update 2/3/21: After deployment and testing, the Dunant cable system is now “ready for service.” Google says its partner SubCom was able to remain on “schedule despite the ongoing global pandemic.”

Original 4/5/19: Dunant spans from Virginia Beach in the United States to a landing station in the French west coast. It is particularly close to the North Virginia and Belgium GCP regions. Google Cloud commissioned it to add capacity and supplement one of the busiest routes on the internet.

In financing its own cable, instead of purchasing capacity on an existing one or building with a consortium, Google has full control of routing and guaranteed bandwidth. This trans-Atlantic cable will transmit 250 Terabits of data per second thanks to space-division multiplexing (SDM). That record-breaking capacity is equivalent to transmitting the entire digitized Library of Congress three times every second.

Instead of six or eight fiber pairs, SDM allows for 12 in a cost-effective manner through power-optimized repeater designs that share resources. As previously announced, Google is working with SubCom to engineer, manufacture, and install the Dunant cable.

Traditional subsea cables are powered from the shore end and rely on a dedicated set of pump lasers to amplify the optical signal for each fiber pair as data traverses the length of the cable. Now, SDM technology allows pump lasers and associated optical components to be shared among multiple fiber pairs, while still working within the unique power constraints of the ocean floor.

The 6,400 km cable comes online in Q3 2020 and is named after Red Cross founder Henry Dunant. Meanwhile, Curie — named after the physicist and chemist — will go live later this year. Google in this case decided to build its own cable between the U.S. and Chile due to the lack of existing infrastructure.