Skip to content 
Importance: Recent advancements in fiber optics have surpassed previous boundaries, achieving a staggering data transmission rate of 1.02 petabits per second—sufficient to download every movie on Netflix 30 times over—across a distance of 1,808 kilometers using a fiber no thicker than a human hair.
Central to this innovation—developed by Japan’s National Institute of Information and Communications Technology (NICT) and Sumitomo Electric Industries— is a 19-core optical fiber featuring a conventional 0.125 mm cladding diameter, allowing for seamless integration into current infrastructure without the need for expensive upgrades.
Each core serves as an independent data channel, together creating a “19-lane highway” within the area of traditional single-core fibers.
In contrast to previous multi-core designs restricted to limited distances or specific wavelength bands, this fiber efficiently operates across the C and L bands (international standards) due to an optimized core arrangement that reduces signal loss by 40% compared to older models.
The success of the experiment depended on a sophisticated recirculating loop system. Signals were transmitted through an 86.1-kilometer fiber segment 21 times, simulating a transcontinental journey like connecting Berlin to Naples or Sapporo to Fukuoka.
To ensure signal integrity over this long distance, researchers implemented a dual-band optical amplification system composed of different devices that strengthened signals in the C and L bands. This setup allowed for 180 distinct wavelengths to transmit data simultaneously using 16QAM modulation, enabling greater information density per pulse.
At the receiving point, a 19-channel detector, equipped with advanced MIMO (multiple-input multiple-output) processing, resolved interference between cores, analogous to disentangling 19 overlapping conversations in a busy environment.
This digital signal processor, utilizing algorithms honed over a decade of multi-core research, extracted usable data at unprecedented efficiency while compensating for distortions accumulated over the lengthy 1,808 km.
This accomplishment culminates years of steady progress. In 2023, the same team achieved 1.7 petabits per second, but only across a distance of 63.5 km. Previous attempts with 4-core fibers managed 0.138 petabits over 12,345 km by engaging the less feasible S-band, while 15-mode fibers encountered signal distortion beyond 1,001 km due to inconsistencies in propagation characteristics.
The innovative 19-core fiber’s even core design circumvents these challenges, realizing a capacity-distance product of 1.86 exabits per second per kilometer—14 times higher than previous records for standard fibers.
Recognized as the premier post-deadline paper at OFC 2025 in San Francisco, this research surface as global data traffic is expected to triple by 2030.
While there are still hurdles, such as improving amplifier efficiency and scaling MIMO processing for practical applications, this technology provides a promising avenue toward petabit-scale networks. Efforts are underway to refine production methods for mass deployment, potentially paving the way for transoceanic cables capable of transferring entire data centers’ worth of information every hour.
Researchers are working on refining production techniques for mass deployment, which could enable transoceanic cables that transport entire data centers’ worth of information every hour.
Engineers at Sumitomo Electric, who developed the fiber’s coupled-core architecture, emphasize that current manufacturing lines can be adapted for the 19-core design with minimal modifications.
In parallel, the NICT team is investigating AI-enhanced signal processing to further elevate speeds. As 6G and quantum computing approaches, this milestone positions fiber optics not only as a cornerstone of future internet architecture but as the essential neural framework of a hyperconnected global network.
