TOKYO – July 2, 2026 – In a milestone that promises to redefine the landscape of telecommunications infrastructure, a collaborative research consortium—comprising the University of Electro-Communications, Lightera Japan Co., Ltd., and Keio University—has announced a breakthrough in optical transmission technology. As part of the “Research and Development Project of Advanced Optical Transmission Technology Contributing to a Green Society,” the team successfully transmitted high-power optical signals exceeding 10 Watts (W) using a hollow-core fiber (HCF) system.
This achievement, which effectively bypasses the physical limitations inherent in traditional silica-core fibers, marks the first time high-quality, high-power data transmission has been realized at such levels. The development paves the way for “ultra-high-branch” Passive Optical Networks (PON) and integrated optical fiber power supply systems, two pillars essential for the future of 5G and beyond.
The Core Innovation: Breaking the Nonlinearity Barrier
The fundamental bottleneck in current optical networking is the physical composition of standard fiber optic cables. Traditional silica-core fibers suffer from nonlinear effects—distortions that occur when the power of transmitted light crosses a certain threshold. These distortions degrade signal quality, effectively capping the amount of data and energy that can be pushed through a single line.
The research team’s solution involves the use of hollow-core fiber (HCF), a cutting-edge medium where light travels through a hollow center filled with air rather than solid glass. Because the light propagates through air, the nonlinear effect is reduced by a factor of approximately 1,000 compared to conventional silica-core fibers. By leveraging this property, the researchers achieved the world’s first successful transmission of communication-grade optical signals at power levels exceeding 10 W.
“We have moved beyond the theoretical limits of legacy glass fibers,” noted a spokesperson from the research group. “By suppressing the nonlinear interference, we have created a pipeline capable of carrying not just information, but significant energy.”
Chronology of the Development
The path to this breakthrough was defined by years of rigorous interdisciplinary research, culminating in the successful experiment conducted earlier this year.
- Early 2023: Under the commission of the Ministry of Internal Affairs and Communications (Project JPMI00316), the consortium was formed to address the energy and scalability demands of next-generation 5G/6G infrastructure.
- Late 2024: The Lightera Group finalized the development of advanced HCF prototypes, designed to minimize signal attenuation and maximize power handling.
- Q1 2026: The team successfully integrated the HCF into an OLT-to-splitter PON architecture. Initial tests were conducted using 5G NR (New Radio) signals at 28 GHz.
- May 2026: The consortium reached the 10 W power threshold while maintaining signal integrity across four multiplexed wavelengths.
- July 2026: Formal announcement of the results, with subsequent publication scheduled for the August 2026 issue of the Journal of Optical Communications and Networking.
Supporting Data and Technical Architecture
The experiment utilized a Wavelength Division Multiplexing (WDM) PON system. By multiplexing four distinct wavelengths modulated by the 5G NR signal at 28 GHz, the researchers demonstrated that high-frequency wireless standards can be carried over long distances without the typical signal degradation associated with high-power transmission.
Technical Performance Metrics:
- Transmission Power: > 10 W (a significant leap over traditional low-power fiber systems).
- Nonlinear Suppression: Approximately 1,000x improvement over silica-core fiber.
- Branching Capacity: The research suggests that the current architecture supports over 4,096 branches, drastically increasing the number of wireless base stations a single OLT (Optical Line Terminal) can service.
- Latency: The HCF medium provides transmission speeds roughly two-thirds faster than traditional single-mode fiber due to the lower refractive index of air compared to glass.
The ability to scale to 4,096 branches is particularly significant for urban environments where the density of 5G small cells and IoT devices is expected to skyrocket.
Implications: A Greener, More Resilient Society
The implications of this development extend far beyond simple data throughput. By enabling "optical fiber power supply," the consortium is addressing a critical vulnerability in current telecommunications: the reliance on local, grid-dependent power for remote base stations.
1. Disaster Resilience
One of the primary goals of the project is to enhance the availability of wireless base stations during natural disasters. By delivering both communication signals and electrical power via the same fiber, base stations can be kept operational even when local power grids are compromised. This creates a "self-healing" or "self-powering" network architecture that is immune to electromagnetic interference and corrosion.
2. The Green Society Initiative
The "Green Society" moniker of the R&D project refers to the efficiency gains inherent in this system. By reducing the need for localized power infrastructure and lowering the number of OLTs required to cover a given area, the energy footprint of mobile networks is significantly reduced.
3. Future-Proofing 5G and IoT
As the world moves toward the integration of smart cities, robotics, and high-frequency IoT sensors, the demand for "massive connections" will reach a fever pitch. The ability to handle high-power optical signals means that future base stations can be smaller, more densely packed, and more efficiently managed, allowing for the widespread deployment of 28 GHz high-frequency services.
Official Responses and Collaborative Vision
The collaboration between the University of Electro-Communications, Lightera Japan, and Keio University represents a unique synergy between academic research and industrial application.
"The success of this project is a testament to what happens when we combine cutting-edge materials science with network architecture," said Professor Motoharu Matsuura of the University of Electro-Communications. "Our goal has always been to solve the bottleneck of current PON systems. Now, we are looking at a future where the fiber optic line is a comprehensive utility for both data and power."
Lightera Japan, representing the global reach of the Furukawa Electric Group’s optical solutions, emphasized the importance of their proprietary HCF technology. "Our HCF is designed specifically to handle the demands of the next century of connectivity," a representative stated. "This experiment confirms that our fiber can handle the high-power, high-density traffic required for 5G, 6G, and the vast IoT ecosystems."
Keio University’s involvement, led by the Future Photonic Network Open Lab, focused on the integration of these signals into existing network fabrics. The team highlighted that while this experiment used four wavelengths, the ultimate roadmap involves multiplexing significantly more, effectively creating a "super-highway" for data and power that can support tens of thousands of connections.
Looking Ahead: The Road to Commercialization
While the current experiment has proven the viability of 10 W transmission over HCF, the research team is already looking toward the next phase. The immediate future involves expanding the wavelength range to accommodate more concurrent signals.
"We have proven that the physics works," the team noted. "The next steps involve refining the power-conversion components at the receiver end (the ONU) to ensure that the optical energy is converted into electricity with maximum efficiency."
As the findings reach the broader scientific community through the Journal of Optical Communications and Networking, the consortium expects to attract further interest from global telecommunications operators looking to upgrade their infrastructure for the 2030s. By solving the dual problem of power delivery and signal capacity, the team has not just built a better fiber—they have built the foundation for a more resilient, efficient, and interconnected global society.
Glossary of Key Terms
- PON (Passive Optical Network): A fiber-optic network architecture that uses unpowered optical splitters to enable a single fiber to serve multiple endpoints.
- Hollow-Core Fiber (HCF): An optical fiber that guides light through a hollow, air-filled core, offering reduced latency and nonlinearities.
- Nonlinear Effect: The distortion of light waves in a fiber, which limits the amount of power that can be transmitted.
- Wavelength Division Multiplexing (WDM): A technique that combines multiple signals onto a single optical fiber by using different wavelengths (colors) of laser light.
- Optical Fiber Power Supply: The use of light to transmit energy through a fiber, which is then converted back into electrical power at the destination.
- 5G NR (New Radio): The global standard for the air interface of 5G mobile networks, particularly those operating in high-frequency bands like 28 GHz.
Contact Information for Research and Media Inquiries:
- University of Electro-Communications: Public Relations, +81-042-443-5019
- Lightera Japan Co., Ltd.: Strategy & Planning, [email protected]
- Keio University: Office of Communications and Public Relations, +81-03-5427-1541
