Colt wraps Multi-Core Fiber (MCF) trial with STL

The trial, which took place in the UK, looks to validate how MCF can work in an active network environment.
Jan. 22, 2026

Key Highlights

  • The trial deployed STL’s Multiverse™ 4-core fiber within Colt’s London metro network, spanning 9 km and 63 km segments.
  • An 800 Gbps line rate was achieved, validating 100GE and 400GE services in a live environment.
  • Extensive testing confirmed the fiber’s performance in chromatic dispersion, crosstalk, throughput, and fault analysis.
  • The MCF technology maintains the same cladding diameter as standard single-mode fiber, enabling easy integration into existing infrastructure.
  • Colt aims to meet rising bandwidth demands while ensuring security, performance, and sustainability through innovative optical solutions.

Colt Technology Services (Colt) completed a trial of Multi-Core Fiber (MCF) with STL across its London, UK, metro optical network, validating the emerging technology in a live network.

During the trial, STL’s Multiverse™ Multi-Core 4-core Fiber—built in the same cladding diameter as standard single-mode fiber (SMF)—was deployed.

The trial was conducted within the London Metro network between two Colt PoPs, spanning 9 km and 63 km. An 800 Gbps line rate was achieved with validation performed for 100GE and 400GigE services.

Colt and STL conducted rigorous testing, including Chromatic Dispersion (CD), Polarization Mode Dispersion (PMD), crosstalk, throughput, fault analysis, OTDR, loss, and optical return loss (ORL), all of which yielded satisfactory results.

STL’s MCF packs 4 cores into the same cladding diameter as standard single-mode fiber (SMF), keeping coating size at 250/200 micrometers and achieving ultra-high transmission capacity per fiber.

“As demand for network capacity surges, customers need more bandwidth without compromising security, performance, or sustainability,” said Buddy Bayer, Chief Operating Officer, Colt Technology Services. “At Colt, we’re pushing the boundaries of optical networking, and this pilot marks a breakthrough across Europe and the USA.”

About the Author

Sean Buckley

Sean is responsible for establishing and executing the editorial strategy of Lightwave across its website, email newsletters, events, and other information products.

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