Multicore Fiber Technology: Advancing Submarine Cable Applications

21 Sep Multicore Fiber Technology: Advancing Submarine Cable Applications

NTT Corporation recently announced the successful completion of a groundbreaking 7,280 km transoceanic transmission experiment using a 12-core multicore fiber. This fiber features 12 optical signal transmission paths within a standard 125 um cladding diameter. This achievement represents a major step forward in next-generation transmission infrastructure, poised to significantly enhance large-capacity optical networks, including future optical submarine cables.

As global demand for bandwidth and faster data transmission continues to rise, multicore fiber (MCF) technology is emerging as a critical solution. In this article, we will explore the significance of this new subsea cable, delve into multicore fibers, examine how they are amplified, and explain why they are particularly suited for submarine applications.

Multicore Fibers

Traditional optical fibers, the foundation of global data transmission networks, usually contain a single core surrounded by cladding with a lower refractive index, guiding light pulses to transmit data. Multicore fibers, however, represent a major shift in technology by incorporating multiple cores within a single cladding. Each core is capable of transmitting its own independent data stream, significantly increasing the fiber’s data-carrying capacity. This concept is known as space division multiplexing (SDM), and it allows for more efficient and scalable data transmission.

The recently announced subsea cable utilizes multicore fiber technology, employing 12-core technology to transmit vast amounts of data across oceans in a single fiber pair. By incorporating multicore fibers into subsea cables, bandwidth can be scaled significantly without the need for additional infrastructure, offering an extremely efficient solution to meet the growing global demand for data.

Advantages of Multicore Fibers

1. Increased Capacity: Multicore fibers offer an exponential increase in data capacity by allowing multiple data streams to be transmitted through different cores within the same fiber.
2. Cost Efficiency: By using a single cable to carry multiple cores, multicore fibers can reduce the overall cost of deployment, maintenance, and equipment compared to laying multiple single-core fibers.
3. Space and Weight Savings: Submarine cable systems are limited by the amount of physical space and weight they can accommodate. Multicore fibers allow for significantly more data transmission without the need for bulky additional cables, making them ideal for submarine applications.
4. Lower Energy Consumption: Multicore fibers reduce the energy required to power multiple transmission systems, especially when paired with advanced amplification technology.

Amplification of Multicore Fibers

A key challenge in submarine cable systems is the need to amplify optical signals over long distances. In traditional systems, erbium-doped fiber amplifiers (EDFAs) are used along the cable route to boost signals and counteract fiber attenuation. However, with multicore fibers, the amplification process becomes more complex due to the presence of multiple cores within a single fiber, requiring more sophisticated amplification techniques.

One amplification strategy involves using single-core EDFAs, which are commonly employed in traditional single-core systems. Adapting these amplifiers for multi-core systems can be a cost-effective solution compared to developing new amplification technologies for each core. However, specialized fan-in fan-out connectors are necessary to link each fiber core in the multi-core fiber to the single-core amplifiers. The losses associated with these connectors, particularly in trans-oceanic applications where many amplifiers are required, can pose challenges. In this specific case, the distances are short, so these losses are unlikely to be a significant concern.

To address the challenges of multi-core systems, multicore EDFAs have been developed. In these amplifiers, the cores are designed to align with the fiber cores. As a result, only one multicore amplifier is needed for each multicore fiber.

Why Multicore Fibers are Critical for Submarine Applications

Submarine communication cables are the backbone of the internet, carrying over 95% of international data traffic. As global data consumption continues to rise, the need for higher capacity cables becomes increasingly critical. Traditional solutions involve laying more cables or increasing the bandwidth of existing cables, both of which come with significant financial and logistical challenges.

Multicore fibers offer a solution to these problems by increasing capacity within the same physical footprint. Here’s why multicore fibers are particularly well-suited for submarine applications:

1. Increased Bandwidth Without Additional Cables

The key benefit of multicore fibers for submarine applications is the ability to significantly boost bandwidth without the need to lay additional cables. In the context of subsea cables, this means fewer deployments, less environmental disruption, and reduced overall cost. A single multicore cable can do the work of several traditional cables, making it a much more efficient solution for high-demand data routes.

2. Space and Weight Constraints

Submarine cables are designed to be durable, lightweight, and capable of withstanding harsh oceanic conditions for decades. Traditional cables with multiple single-core fibers require a larger physical footprint and greater weight, which increases the complexity of deployment. Multicore fibers, on the other hand, allow for more data transmission capacity within a smaller, lighter cable, making them ideal for deep-sea applications where space and weight are at a premium.

3. Cost-Effective Scaling

Scaling up data capacity in submarine cable systems is notoriously expensive. Multicore fibers reduce the need for constant upgrades by offering a long-term, scalable solution that can grow with future data demands. This is especially critical for regions where high data growth is anticipated, such as between Europe and the Nordic countries.

4. Energy Efficiency

The energy required to operate a submarine cable system is significant, especially over long distances. Multicore fibers, when paired with advanced amplification technology, can reduce the overall energy consumption of the system. This is particularly important in a world where both environmental impact and operational efficiency are growing concerns.

Conclusion

The experimental 12 core subsea cable marks a significant achievement in the world of submarine communication. With the introduction of multicore fiber technology, we are witnessing the future of high-capacity data transmission, where bandwidth can be exponentially increased without the need for additional infrastructure. Multicore fibers, combined with advanced amplification techniques, are critical for overcoming the challenges of long-distance submarine cables. As global data needs continue to grow, multicore fibers will play a key role in ensuring the continued expansion and efficiency of the world’s communication networks.

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Jabulani Dhliwayo

Founder and Technical Director at FiberGuide, Lecturer, Scientist and Engineer. Passionate about optical networking and information and communication technologies. Connect with me on Linkedin – https://www.linkedin.com/in/jabulani-dhliwayo-1570b5b