The Groundbreaking Achievement by NICT Researchers
In a monumental leap for optical communications, researchers from Japan's National Institute of Information and Communications Technology (NICT) have shattered world records by transmitting data at 1.02 petabits per second (Pb/s) over a staggering distance of 1,808.1 kilometers. This ultra-high-speed data transmission record equates to over 1 million gigabytes per second, capable of downloading the entire Netflix catalog in mere moments. The feat was accomplished using a novel 19-core randomly-coupled multi-core fiber (MCF) with a standard cladding diameter of 0.125 mm, ensuring compatibility with existing infrastructure.
Announced on May 29, 2025, this breakthrough was detailed in a post-deadline paper at the Optical Fiber Communication Conference (OFC 2025), titled "1.02 Petabit/s Transmission Over 1,808.1 km in a 19-Core Randomly-Coupled Multicore Fiber." It marks the first petabit-class transmission exceeding 1,000 km in standard 19-core fiber, addressing the explosive data demands of the post-5G era.
Evolution of Optical Fiber Technology: From Single-Core to Multi-Core
Optical fiber communication has evolved dramatically since the 1970s when single-mode fibers first enabled gigabit speeds. Traditional single-core fibers, with one light path (core) surrounded by cladding, hit capacity limits around 100 terabits per second (Tb/s) due to the Shannon limit and nonlinear effects. To scale, researchers turned to space-division multiplexing (SDM), packing multiple cores or modes into one fiber.
Multi-core fibers (MCFs) emerged in the 2010s, initially uncoupled (isolated cores) then coupled for uniform performance. NICT's 19-core MCF uses random coupling, where light mixes between cores, simplifying manufacturing and enabling MIMO (multiple-input multiple-output) digital signal processing (DSP) to decode signals, akin to Wi-Fi MIMO. This design maintains low loss across C-band (1,530-1,565 nm) and L-band (1,565-1,625 nm), critical for long-haul transmission.
Step-by-Step Breakdown of the Record-Setting Experiment
The setup involved a recirculating loop system simulating real-world deployment:
- Signal Generation: 180 wavelengths across C+L bands modulated with polarization-multiplexed 16QAM (quadrature amplitude modulation), branched into 19 cores with deliberate delays to simulate distinct paths.
- Transmission Loop: Each 86.1 km loop of 19-core fiber, repeated 21 times for 1,808 km total. Loops included multiplexers/demultiplexers and amplifiers.
- Amplification: Custom 19-core amplifiers for C and L bands separately, compensating losses (~0.18 dB/km).
- Reception and DSP: Coherent detection per core, followed by offline MIMO-DSP to mitigate inter-core crosstalk, yielding 1.02 Pb/s post-FEC (forward error correction).
This closed-loop approach validated stability over ultra-long distances.OFC 2025 paper abstract
Key Innovations: Random Coupling and MIMO-DSP
The randomly-coupled MCF avoids precise core spacing, reducing fabrication complexity. Light scrambling between cores creates uniform propagation, unlike uncoupled MCFs needing S-band amplifiers (not commercial). MIMO-DSP, processing 19x19 matrices, handles interference like massive MIMO in wireless.
Sumitomo Electric optimized core pitch and trench-assisted design for low loss and crosstalk. Amplifiers used multicore EDFAs (erbium-doped fiber amplifiers), a first for 19 cores over such distance.
Comparison to Previous Records and NICT's Track Record
| Record | Speed | Distance | Fiber Type | Date |
|---|---|---|---|---|
| NICT 2025 (New) | 1.02 Pb/s | 1,808 km | 19-core coupled MCF | May 2025 |
| NICT Previous | 0.273 Pb/s | 1,001 km | 15-mode fiber | ~2024 |
| NICT Short-range | 1.7 Pb/s | 63.5 km | 19-core MCF | Prior |
| NICT Standard SMF | 402 Tb/s | 50 km | Single-mode | Jun 2024 |
Capacity-distance product: 1.86 Eb/s·km, highest for standard fibers.
The Research Team and International Collaboration
Lead authors include Ruben S. Luis, Georg Rademacher, Benjamin J. Puttnam from NICT, with contributions from Yuki Goto (NICT), Takuji Nagashima, Taiji Hayashi (Sumitomo), and internationals like Martijn van der Hout (Eindhoven Tech), Stefano Gaiani (Politecnico di Milano). Hideyuki Furukawa (NICT) oversaw.
This showcases Japan's photonics prowess, bolstered by global academia.
Implications for 6G, Data Centers, and Submarine Cables
For 6G (expected 2030s), this scales capacity 100x beyond 5G fibers. Data centers handling AI (e.g., GPT models need exabytes) benefit from intra-DC links. Submarine cables, spanning oceans, could upgrade to MCF for trans-Pacific routes.NICT press release details future infrastructure
Japan leads with investments in photonics; NICT's IOWN initiative with NTT aims for 125 Pb/s systems.
Japan's Leadership in Photonics Research
Japan dominates optical comm records (over 50% recent highs), thanks to NICT (est. 2004), Sumitomo, Furukawa Electric. Universities like Tokyo Tech, Osaka Univ contribute. Ties to higher ed via joint labs, training photonics PhDs for industry.
Challenges: talent retention amid global competition; solutions include MEXT funding, industry-academia pacts.
Overcoming Challenges and Future Directions
Challenges: inter-core crosstalk, amplifier scalability, DSP complexity (high compute). Overcome via random coupling, custom amps, advanced FEC.
Future: >10 Pb/s with more bands/cores, integration with photonic ICs, field trials. "Major step toward scalable networks," per NICT.
Photo by Nomadic Julien on Unsplash
Broader Impacts on Society and Economy
This fuels digital economy: telemedicine, VR/AR, autonomous systems. Environmentally, efficient fibers cut energy (optics 100x less power than copper). Japan positions as 6G exporter, boosting jobs in research.Sumitomo's fiber role
For academics: spurs MCF PhD research, collaborations.
