STL
STL completes successful Multi-Core Fiber (MCF) trial with Colt in London, UK
India based STL, a global provider of optical and digital connectivity solutions for AI-era networks, has completed multi-core fiber (MCF) field trials with Colt Technology Services on Colt’s London metro optical network. The trial is a meaningful proof point for space-division multiplexing (SDM) in carrier environments, demonstrating that MCF can lift per-fiber strand capacity while staying within existing civil and duct constraints and improving overall network energy and cost metrics.
The deployment used STL’s Multiverse™ four-core MCF, designed with the same 125 µm cladding diameter as conventional single-mode fibre (SMF) and a 250/200 µm coating, enabling seamless handling with existing cable designs and installation practices. The trial route connected two Colt Points of Presence (PoPs) on the London metro network over spans of approximately 9 km and 63 km, representing both short-haul metro and longer metro-regional use cases.
From a transmission standpoint, the network achieved an 800 Gbps line rate with service validation for 100GE and 400GE, aligning with current high-capacity router and data-centre interconnect interfaces. STL and Colt validated performance across a broad set of optical and system parameters, including chromatic dispersion (CD), polarization mode dispersion (PMD), inter-core crosstalk, throughput, fault behavior, OTDR signatures, insertion loss, and optical return loss (ORL), with results within expected design envelopes. This indicates that Multiverse™ MCF can be engineered and operated to comparable performance baselines as legacy SMF while delivering higher spatial capacity.
Architecturally, STL’s MCF platform integrates four independent cores within a standard SMF cladding profile, effectively multiplying per-fibre capacity without increasing cable diameter. For operators, this directly addresses constraints in congested metro ducts, legacy civil infrastructure, and brownfield routes where augmenting capacity by pulling additional cables is either cost-prohibitive or operationally disruptive. In these scenarios, MCF creates a higher bit-per-mm² and bit-per-duct investment profile, improving both capex efficiency (less civil work, fewer ducts) and opex metrics such as energy per transported bit.
STL positions itself as one of the early movers in taking MCF from controlled lab demonstrations into operational networks, including buried and ducted plant, backed by a full ecosystem spanning fibre, cable, and connectivity hardware through its Optotec portfolio. Coupled with STL’s broader focus on AI-ready optical infrastructure and 5G-ready digital network solutions, the Colt trial underlines a practical migration path for carriers looking to future-proof metro and data-centre interconnect footprints against emerging AI, cloud, and 5G traffic patterns without wholesale rebuilds of underlying passive infrastructure.
“As network demand accelerates, customers are looking for more bandwidth without sacrificing security, performance, or sustainability,” said Buddy Bayer, Chief Operating Officer, Colt Technology Services. “At Colt, we continue to push optical networking forward, and this pilot represents an important step in Europe and the USA. It reflects our focus on building scalable networks that deliver growth in capacity without increasing environmental impact.”
Dr Badri Gomatam, CTO, STL, said the trial highlights the value of joint innovation in advancing optical infrastructure. “Collaborations like this speed up adoption of next-generation connectivity technologies. STL’s Multiverse MCF portfolio is designed for the high-density, ultra-low latency, and resilient connectivity requirements of AI, hyperscale cloud, and future digital platforms globally,” he said. STL stated that the trial results strengthen confidence in MCF as a viable technology for the growing bandwidth requirements driven by AI workloads, cloud scale-out, and new digital services.
“As network demand accelerates, customers are looking for more bandwidth without sacrificing security, performance, or sustainability,” said Buddy Bayer, Chief Operating Officer, Colt Technology Services. “At Colt, we continue to push optical networking forward, and this pilot represents an important step in Europe and the USA. It reflects our focus on building scalable networks that deliver growth in capacity without increasing environmental impact.”
Dr Badri Gomatam, CTO, STL, said the trial highlights the value of joint innovation in advancing optical infrastructure. “Collaborations like this speed up adoption of next-generation connectivity technologies. STL’s Multiverse MCF portfolio is designed for the high-density, ultra-low latency, and resilient connectivity requirements of AI, hyperscale cloud, and future digital platforms globally,” he said. STL stated that the trial results strengthen confidence in MCF as a viable technology for the growing bandwidth requirements driven by AI workloads, cloud scale-out, and new digital services.
………………………………………………………………………………………………………………………………………………………………….
About STL-– Sterlite Technologies Ltd:
STL is a global provider of advanced connectivity solutions, offering end-to-end products and services for building AI-ready networks across FTTx, rural broadband, enterprise, and data centres. With manufacturing operations in North America, Europe, and Asia, STL supplies connectivity solutions in more than 100 countries and works with telecom operators, cloud and data center companies, internet service providers, and large enterprises to build future-ready AI digital infrastructure.
On January 23, 2026, STL reported continued sequential improvement in Operational EBITDA margin for the fifth consecutive quarter, driven by a higher-margin product mix and increased contribution from the US market. With the US–India Bilateral Trade Agreement under advanced discussion, STL remains well-positioned to leverage emerging opportunities by offering reliable, high-quality solutions for building AI-ready digital infrastructure.
……………………………………………………………………………………………………………………………………………………
References:
https://www.intechopen.com/chapters/78908
How will fiber and equipment vendors meet the increased demand for fiber optics in 2026 due to AI data center buildouts?
Big tech spending on AI data centers and
AT&T sets 1.6 Tbps long distance speed record on its white box based fiber optic network
