IEEE ComSoc Technology Blog

Introduction:

A foundational enabler of global AI infrastructure and cloud service expansion are the fiber-optic networks interconnecting data centers worldwide. These high-capacity optical systems form the invisible backbone of modern digital society, facilitating everything from real-time financial transactions and mission-critical enterprise traffic to defense systems, entertainment, and personal communications.  Access to cloud-based AI platforms—and the data-driven intelligence they deliver—depends on efficient, low-latency connectivity to data centers. As AI workloads proliferate across industries and continents, the unifying role of optical fiber becomes paramount, ensuring equitable global access to advanced digital capabilities.

A core prerequisite for scaling AI and cloud services is the mesh of high-capacity fiber-optic networks that interconnect data centers globally. These networks silently underpin digital society, carrying the data that powers financial markets, mission-critical enterprise applications, national security, entertainment platforms, and everyday human communication.​

Cloud-based AI services only become meaningful when users, enterprises, and machines can reach them with low latency, high reliability, and predictable performance. In this context, the unifying role of fiber is increasingly strategic, as it determines who can participate in the AI economy and at what scale.

Subsea (fiber) cable systems as digital unifier:

The massive capacity and spectral efficiency of optical fiber have driven its deployment from access networks to backbone routes and across the world’s oceans. Today, more than 570 subsea cables carry over 99% of international traffic, effectively stitching together a single global fabric for AI and cloud connectivity.​

New subsea systems highlight how infrastructure investments are closing regional gaps rather than just adding raw terabits: the Medusa submarine cable system will help narrow the digital divide between Europe and North Africa, the Bangladesh Private Cable System (BPCS) will establish the country’s first private subsea on-ramps to global cloud and AI ecosystems, and a new Jakarta–Singapore route by PT Solusi Sinergi Digital Tbk (Surge) is set to increase data center interconnectivity while expanding affordable broadband to tens of millions of Indonesians.​

As multiple new subsea cable system build outs enter planning and deployment, global bandwidth growth is expected to remain strong, extending the reach of AI and cloud platforms to more geographies, users, and industries.​

From PoPs to data centers:

The traffic matrix of the AI era looks very different from that of legacy telecom networks. Instead of primarily connecting PoPs, carrier hotels, and central offices, modern optical networks are being engineered around dense, high-capacity flows between data centers.​

More than 11,000 data centers, including over one thousand hyperscale facilities, now form the core nodes of the global digital infrastructure, generating on the order of thousands of petabytes of WAN traffic daily. Subsea bandwidth demand is expected to grow at roughly 30% per year as AI and cloud services scale, placing new design pressure on how subsea and terrestrial backhaul networks are engineered end-to-end.​

Unifying subsea and terrestrial backhaul:

This shift is driving a deliberate architectural pivot: instead of treating subsea and terrestrial backhaul as separate domains, leading operators and cloud providers are moving toward unified, end-to-end design philosophies. Traffic no longer “terminates” at a cable landing station or central office; it flows optically and logically from data center to data center across continents.​

By optimizing subsea and terrestrial segments as a single system, operators can simplify their networks, reduce CapEx and OpEx, and unlock higher effective capacity. Approaches such as optical pass-through at cable landing sites reduce cost, footprint, and power, while spectrum expansion into C+L bands can deliver a twofold or greater increase in per-fiber capacity, significantly lowering the cost of backhauling subsea traffic to inland data centers.

An ever-increasing number of data centers powering AI services is driving significant bandwidth growth over subsea fiber optic cables. ​ Image Credit: Nokia

Unified optical platforms for the AI supercycle:

Realizing this vision at scale requires platforms that unify roles traditionally split across multiple, specialized systems. For Nokia’s customers, this means leveraging the 1830 Global Express (GX) compact modular portfolio as a single, DCI-optimized solution for transponders, open optical line systems (OLS), and submarine line terminal equipment (SLTE) across both subsea and terrestrial applications.​

High-performance coherent transponders on the 1830 GX support 800 Gigabit Ethernet across trans-oceanic distances, using techniques such as Probabilistic Constellation Shaping, Nyquist filtering, and continuous baud rate tuning to push performance toward the Shannon limit. The integrated OLS delivers the full suite of SLTE capabilities, including ROADM-based wavelength switching and spectrum management, ASE or CW idler insertion, and optical channel monitoring, while C+L operation on terrestrial backhaul provides step-function increases in capacity per fiber and reduces the cost of leased backhaul infrastructure.

Photo Credit: Nokia​

Operational simplicity and resilience:

Beyond raw capacity, unified platforms enable operators to rationalize operations. Using a common hardware and software stack across subsea and terrestrial domains simplifies planning, training, sparing, deployment, and lifecycle management.​

Capabilities such as constant-power ILAs for stable end-to-end DC-to-DC transport, integrated OTDR for proactive fiber monitoring and fault localization, and a rich set of optical protection schemes for service protection and restoration help operators build networks that are not only faster and denser, but also more resilient and easier to run.​

What’s next: pluggables and sensing:

The industry is now entering a phase where innovation in optics is tightly coupled to AI and automation. At PTC 2026 in Honolulu, discussions will highlight how pluggable coherent optics and fiber sensing are being introduced into subsea environments to further collapse layers and enhance awareness.​

ICE-X 800G coherent pluggables are already enabling 400G, 600G, and 800G per wavelength over regional subsea spans exceeding 4,000 km, and future advances in chromatic dispersion tolerance are expected to extend the thin transponder layer paradigm to trans-Atlantic routes. In parallel, operators are exploring fiber sensing, powered by machine learning and advanced coherent techniques, to transform existing fiber assets into distributed sensors capable of supporting security, integrity monitoring, and new data-driven services.​

Connectivity for all:

“Advancing connectivity for the AI supercycle” is more than a tagline; it captures two simultaneous imperatives: scaling networks for performance, efficiency, and sustainability while extending those networks to every region and community.  As described herein, fiber optics connectivity is becoming the strategic control point for value creation in the age of large-scale AI.​

Nokia’s Role in Subsea Fiber Optic Networks:

Nokia has invested for more than 15 years in helping subsea operators and their customers design, deploy, and operate end-to-end SLTE and terrestrial optical networks, backed by global services and multi-country program support. Following its unification with Infinera, Nokia has emerged as the number-two global vendor of subsea optical transport equipment, earning the confidence of a large majority of operators involved in the latest wave of Asia-Pacific subsea builds. These partnerships position Nokia to help the industry scale and unify networks for the AI supercycle—and to ensure that the benefits of AI-era connectivity reach as many people, countries, and enterprises as possible.

Nokia’s 1830 Global Express (GX) supports high-performance coherent transponders for transmission of high-speed data connections such as 800 Gigabit Ethernet (800GE) across trans-oceanic distances, leveraging features such as Probabilistic Constellation Shaping (PCS), Nyquist filtering and continuous baud rate adjustment to maximize optical reach and fiber capacity up to the Shannon Limit. The 1830 GX OLS supports all needed SLTE functions including ROADM-based wavelength switching and spectrum management, insertion of ASE spectrum or continuous-wave (CW) idler channels, and optical channel monitor.

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References:

https://www.nokia.com/blog/the-unifying-role-of-subsea-fiber-networks/

https://www.nokia.com/optical-networks/1830-global-express/

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