Colt UK Trial 800Gbps Multi-Core Fibre Cable on Metro Optical Network in London

Business communications and internet provider Colt Technology Services (COLT) has joined forces with connectivity solutions provider STL (Sterlite Technologies) to successfully trial a new Multi-Core Fibre (MCF) cable – specifically STL’s Multiverse™ Multi-Core 4-core Fibre – across their metro optical network in London.

The new cable, which promises to deliver high-capacities across a cost-efficient backbone for next-generation networks, was built in the same cladding diameter as standard Single-Mode Fibre (SMF) cables – keeping coating size at 250/200 micrometres. The trial itself was conducted within the London Metro network between two of Colt Points of Presence (PoPs), covering distances of around 9km and 63km.

The trial is said to have successfully achieved an 800Gbps (Gigabits per second) line rate, including validation being performed for 100GE and 400GE services. Various tests were also carried out, such as Chromatic Dispersion (CD), Polarization Mode Dispersion (PMD), Crosstalk, Throughput, Fault analysis, OTDR, Loss, and Optical Return Loss (ORL) measurements, all of which are said to have “delivered satisfactory results“.

Buddy Bayer, Chief Operating Officer at Colt, said:

“As demand for network capacity surges, customers need more bandwidth without compromising security, performance, or sustainability. At Colt, we’re pushing the boundaries of optical networking, and this pilot marks a breakthrough across Europe and the USA. It demonstrates our commitment to delivering future-ready, sustainable networks that meet growing needs without costing the earth.”

Dr. Badri Gomatam, CTO of STL, added:

“Partnerships like these exemplify how collaborative innovation can accelerate the evolution of optical infrastructure. STL’s Multiverse MCF portfolio is engineered to meet the high-density, ultra-low latency, and resilient connectivity demands of AI, hyperscale cloud, and next-generation digital ecosystems worldwide.”

At present MCF cables are still relatively new (commercially speaking) and their main selling point is that ability to significantly increase throughput, albeit within cables of a similar or the same physical size to what went before. This makes them particularly handy for tackling high-demand scenarios like data centres, national fibre links, and international submarine cables.

On the flip side, MCF cables can be more complex to splice together and there are some issues with standardisation to consider. Such cables may also compete with future Hollow-Core Fibres (HCF), which can offer faster latency times but are a bit more niche in their ideal use cases. But HCF is still somewhat of a work-in-progress technology and may carry added costs.

STL is currently one of the first companies globally to take MCF from the lab to real-world environments, spanning underground and duct networks with a complete ecosystem of fibres, cables, and termination solutions. The new trial helps to validate this and could lead to more deployments in the future.