Subsea multi-core fiber advances

In this Master Class led by Masaaki Hirano , Product Manager for Optical Fiber at Sumitomo Electric Industries, Ltd., we'll uncover the story behind the scenes—tracing a legacy dating back to 1971 and reaching forward to the forefront of subsea communication technology in 2023.

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Sumitomo Electric , a name that echoes a rich legacy, began its fiber development venture in 1971 using the VAD method. Over the years, we've etched our mark in the industry, and in 2015, the IEEE Milestone award recognized our relentless pursuit of innovation. From supplying the first pure silica core fiber, Z Fiber, for the Transpacific Cable TPC-4 project in 1989 to contributing to the world's first transoceanic full-digital coherent system with Z-PLUS Fiber 130 in 2014, our journey has been one of continuous exploration.

In September 2023, we proudly unveiled the world's first subsea 2-core fiber mass production – Z-PLUS ULL. Today, I'm eager to walk you through the intricacies of this pioneering technology and its implications for the future of subsea communications.

Evolution of Subsea Transition:

Embarking on a stroll down the memory lane of subsea cable capacity evolution, Sumitomo Electric's central role becomes evident. Every five years, we've witnessed the emergence and disappearance of various transmission technologies and fiber standards, navigating the dynamic nature of the industry with adaptability as our guiding principle. This journey unveils Sumitomo Electric's integral position, where the dynamic industry landscape underscores the need for adaptability—a principle that guides us at Sumitomo Electric.

Digital Coherent Technology:

An important moment in our exploration unfolded around 2014. The historical chart of transmission loss improvement, which had remained stable for almost two decades, experienced a paradigm shift. This marked the year we supplied fiber to fully digital coherent systems, ushering in a new era of enhanced attenuation. Sumitomo Electric played a vital role in this transformation, driving advancements in mass production and research and development.

Space Division Multiplexing:

As we navigate through the evolution, Space Division Multiplexing (SDM) takes center stage. Shannon's equation guides us through the intricacies of transmission capacity, introducing the concept of SDM channels – the number of cores in a single cable. Challenges arise with increased fiber density, accentuating the importance of low microbending loss for SDM systems. At Sumitomo Electric, we're not just navigating these challenges; we're thriving in this dynamic and evolving environment.

Evolution of Subsea Fiber:

The dynamics of the subsea fiber industry unfold with shifts from larger effective area fibers to optimized effective area fibers. Challenges emerge, as seen in the investment in 130 and 150 fibers, which underwent a dramatic shift just two years later. Yet, our commitment to contributing to subsea transmission capacity enhancements remains steadfast, adapting to the industry's inherent uncertainties.

2-Core Fiber Technology:

Now, let's explore the essence of my presentation—the transformative potential of 2-core fiber in revolutionizing cable capacities. Our journey towards a one petabit cable becomes clear as we showcase the feasibility of achieving this milestone by incorporating two cores in a single fiber. Recent announcements from industry giants further validate the practicality of subsea multi-core fiber technology for real-world applications, underscoring Sumitomo Electric's pioneering stance.

The significance of this lies not just in the technological advancement but in a milestone that propels the industry into a new era of subsea communication. The specifications of this 2-core fiber boast equivalence to single-core fiber in terms of cladding and fiber diameter. Parameters such as crosstalk, polarization mode dispersion (PMD), and proof test level are dissected, revealing Sumitomo Electric's commitment to performance, reliability, and continuous improvement.

World's First Subsea Multi-Core Fiber Mass Production:

The zenith of our presentation is the announcement of the world's first subsea multi-core fiber mass production—Z-PLUS ULL. The specifications of this 2-core fiber boast equivalence to single-core fiber in terms of cladding and fiber diameter. Parameters such as crosstalk, polarization mode dispersion (PMD), and proof test level are dissected, revealing Sumitomo Electric's commitment to performance, reliability, and continuous improvement. The unveiling of Z-PLUS ULL signifies not just a technological advancement but a milestone that propels the industry into a new era of subsea communication.

2-Core Fiber Design and Ecosystem:

Transitioning to the design considerations for 2-core fiber, we shed light on Sumitomo Electric's approach. The shifted configuration, allowing for easy identification and splicing loss management, presents a practical solution. The polarity-free handling of this configuration contributes to reduced total costs, creating a seamless and evolving ecosystem. Leveraging existing technologies like SLTE and EDFA, along with a focus on standardization, Sumitomo Electric aims to provide a robust foundation for the widespread adoption of 2-core fiber.

Challenges and Ongoing Improvements:

Acknowledging the challenges inherent in the industry, I emphasize our ongoing improvements. Sumitomo Electric's pursuit of a 0.150 dB per kilometer 2-core fiber stands as a testament to our commitment to pushing the boundaries of what's possible. Looking ahead, the potential of 4-core fiber looms on the horizon, presenting both challenges and opportunities. The role of amplifier technology becomes pivotal in further ramping up cable capacity, and we explore 4-core fiber as a potential solution to meet the ever-growing demands of the industry.

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In conclusion, the journey through Sumitomo Electric's subsea fiber innovations is a testament to our commitment to pushing the boundaries of what's possible. As we navigate this complex and ever-changing landscape, our collaborative spirit and innovation serve as beacons guiding the way forward. The future of subsea communications promises to be exciting, and at Sumitomo Electric, we're ready to shape it.

Watch the full video: https://youtu.be/9heVh-M2KJI