STEVE ROBERTS LONG-HAUL CONNECTIVITY
influencing how fibre networks are designed, built, and operated. These organisations now demand massively scalable bandwidth to support cloud services, AI model training, and data-intensive applications. Not only this, but they also require ultra-low latency for time-sensitive services like high-frequency trading, gaming, and real-time analytics. Reliability is non-negotiable, with mission- critical workloads pushing for near-zero downtime. Ultimately, fibre can no longer remain static, and we are now seeing a shift in its evolution to meet the demands of a dynamic digital future. THE STRATEGIC SHIFT This shift is already influencing how network operators approach fibre infrastructure, from the physical characteristics of the cable itself to the long-term economics of deployment and maintenance. To support bandwidth growth and ultra- high-speed optics like 400G and 800G coherent transmission (and eventually 1.6T), operators are prioritising lower attenuation and larger effective area in their fibre designs to reduce regeneration needs and minimise nonlinear signal impairments. They are also moving beyond a narrow focus on upfront capital expenditure toward a lifecycle value approach. The key question is no longer, “What is the cheapest fibre to install today?”, but rather, “What fibre will deliver the best performance, lowest operational cost, and greatest flexibility over the next 20 years?”. A more expensive fibre today might reduce operational expenditures by requiring fewer amplifiers, simplifying upgrades, or avoiding route re- engineering - it may even future-proof the network to support future transmission technologies. Network architects are rethinking how they build. Increasingly, they are turning to modular, scalable infrastructure that can grow incrementally and adapt as technology evolves. This means deploying fibre mixes tailored to the role of each segment, such as G.652.D for metro and access, G.654.C/E for long-haul backbones, and hollow-core fibre (HCF) for latency-critical routes. They are also favouring software-defined control layers over flexible fibre topologies, supporting dynamic capacity allocation and automation. So, what is the main takeaway here? Fibre selection is becoming a long-term strategic decision, not just an engineering one. WHAT’S ON THE HORIZON? With these new trends in mind, G.654C fibre has emerged as a top contender for modern fibre deployments. Originally, G.654C was developed for submarine cable systems, where ultra- long spans between amplification points
(often hundreds of kilometres apart) made low attenuation and signal integrity critical. The success of G.654C in undersea environments has led to its growing appeal in terrestrial ultra-long-haul deployments, especially where fibre spans stretch between major cities, data centres, or across national borders. As demand for 400G and 800G transport continues to rise, G.654.C fibre is increasingly recognised as a strategic choice for building future-ready terrestrial networks. Its design enables optical signals to travel further without amplification, reducing the need for regenerators or optical amplifiers. With a larger core that spreads the optical signal, G.654.C also helps mitigate nonlinear optical effects such as self-phase modulation and cross-phase modulation. Additionally, it is optimised for coherent optical systems, which use advanced phase and amplitude modulation techniques to encode more data onto each light wave. However, G.654C fibre is no silver bullet for the modern fibre network. After all, there is no ‘one-size-fits-all’ solution. Different applications, geographies, and cost models all require diverse fibre types to optimally balance performance, reliability, and economics - emerging fibres only expand the toolkit for network designers. Take G.654E fibre, for example. It is similar to G.654C in that it offers very low attenuation and large effective areas; however, it differs in bend tolerance. G.654E improves on G.654C by providing better resistance to bending losses, making it even more suitable for terrestrial environments with tighter ducts and frequent splicing. As networks become denser and more complex, having a fibre that can handle tighter bends without significant signal loss opens up new design possibilities, especially in urban or congested environments. We can also consider Hollow Core Fibre (HCF) as another fibre option for network designers. HCF is an advanced type of optical fibre where light travels through a hollow air-filled core instead of a solid glass core. While the concept behind HCF is not entirely new, dating back to the 19th century, its practical application in telecommunications is relatively recent. The air core reduces latency by up to 30%, a game-changer for latency-sensitive applications like high-frequency trading, real-time cloud gaming, or scientific data transfer. HCF’s unique light guidance mechanisms can also support bandwidth levels that are difficult to achieve with traditional solid-core fibres, potentially redefining capacity limits in specialised scenarios. Although still in early stages, and of course, not without its limitations – including high manufacturing and installation costs, complex splicing requirements - HCF is being actively developed and tested. Understanding its potential and limitations is critical for
forward-looking network planners aiming to stay ahead of the curve. Many modern fibres can provide excellent optical performance across different applications, but achieving that potential in real-world deployments depends on rigorous installation and maintenance practices. The attenuation advantages of premium fibre can be quickly eroded by poor installation, such as excessive splice losses, microbending, or substandard mid-span connectors. While reflectance - a key parameter for RAMAN amplifiers in high-performance optical systems - can be degraded by incorrect or excessive connector use and poor fusion splicing. Fibre installed in shallow-buried ducts is especially vulnerable to third-party construction damage, with each poorly executed repair adding further splice losses. Network design is equally critical: optimal spacing of equipment shelters for in-line amplifiers (ILAs) is essential to boost optical signals at regular intervals. If ILAs are placed too close together or too far apart, both performance and economics suffer. THE FUTURE OF FIBRE DEMANDS SMART CHOICES BEYOND THE CABLE Fibre system performance is shaped not only by the cable type but also by the operator’s installation and maintenance standards, as well as the physical characteristics of ducts and equipment shelters. For network planners and operators, the path forward lies in making informed, strategic choices - balancing performance, cost, and long-term flexibility to build fibre infrastructure ready for whatever comes next.
Steve Roberts is SVP Strategic Network Investments and Product Management at EXA Infrastructure, where he leads the company’s organic network expansion strategy and product portfolio. Passionate about building large- scale infrastructure, his team drives investments in new terrestrial routes, subsea systems and datacentre connectivity. Steve has also held senior leadership roles at GTT, Interoute and Vtesse, where he led international teams across product management, network investment, technical sales and strategy.
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ISSUE 42 | Q3 2025
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