Cisco announced they have successfully transmitted 800Gbps on the Amitié transatlantic submarine cable, which runs 6,234 kilometers from Boston, Massachusetts to Bordeaux, France. 

The 800Gbps transmission trial was done in collaboration with Microsoft, to support their exponential growth in cloud and AI services which requires increased subsea network capacity to improve overall network performance.

Microsoft is a member of the Amitié consortium, in addition to Aqua Comms, Meta, and Vodafone (through Cable & Wireless Americas Systems, Inc.). 

Amitié submarine cable features Space Division Multiplexing (SDM) technology with 16 fiber pairs on its transatlantic trunk and 12 fiber pairs from BU1 to Bude, UK and La Porge, France, respectively. Using SDM technology, Amitié consists of more fiber pairs than traditional subsea cables, with repeater power shared across the fiber pairs to deliver the highest cable capacity.  

The Amitié cable system was ready for service in July 2023, supplied by ASN, initially designed with a system capacity of 320 Tbps, or 20 Tbps per fiber pair.

Amitié Cable Route


The continued growth of cloud and explosion of AI services is driving the need for greater subsea network capacity, which requires advanced coherent transmission systems that support higher performance. This trial was conducted to target improvements in subsea transmission to provide increased performance and capacity. 

This real-time field trial exceeded any industry trial performance to date with Dense Wavelength Division Multiplexing (DWDM) 800G in a 150GHz channel spacing, equivalent to a spectrum efficiency of 5.33bit/s/Hz and a maximum spectral efficiency of 5.6bit/s/Hz. In addition, 600G was transmitted over 12,469 kilometers for a trans-Atlantic loopback configuration. This is the first time a 140Gbaud single carrier signal was demonstrated live, and is the longest distance ever reported at single carrier 600G DWDM transmission on an SDM cable. 

“In the era of AI, reliable and fast network connections are more important than ever,” said Bill Gartner, SVP Optical Systems and Optics, Cisco. “Working with Microsoft on the Amitié cable to demonstrate the potential for improved overall network capacity with 800G at these distances is a significant milestone for an SDM cable, and we’re proud to drive the innovations that pave the way for ever increasing network capacity needs.”   

“The transmission of 800G over 6,234 kilometers is a milestone that demonstrates SDM cables can deliver increased capacity over traditional subsea cables,” said Jamie Gaudette, GM of Cloud Network Engineering, Microsoft. “This field trial demonstrates what is now a commercial technology for subsea routes, and we can improve the network capacity to help drive digital transformation for people, organizations, and industries around the world.” 

The trial was performed with the Cisco NCS 1014 platform enabled by Acacia’s Coherent Interconnect Module 8 (CIM 8), which is powered by its Jannu digital signal processor and advanced silicon photonics.  Both products are available today and actively deployed in multiple networks. 

The deployment of 800Gbps will increase the capacity per fiber pair from its current 20Tbps to approximately 24Tbps, or a 20% incremental capacity.

Acacia, acquired by Cisco in 2021, achieved a spectral efficiency of 6.41 b/s/Hz on the 6,644 km Marea transatlantic cable in 2018, utilizing Acacia’s patented Fractional QAM modulation and 400G coherent optic transmission technology. 

Infinera achieved a spectral efficiency of 6.21 b/s/Hz or a capacity per fiber pair of 26.2Tbps on the Marea transatlantic cable, prior to Acacia's trial.