Japanese researchers have achieved a major milestone in the race toward 6G by transmitting data wirelessly at 112 gigabits per second through the 560 GHz terahertz band.
The achievement is important not only because the speed exceeded 100 Gbps, but because it did so at a frequency above 420 GHz. Previous systems operating at such extreme frequencies were generally limited by weak output power, unstable signals and phase noise.
The research team, led by scientists at Tokushima University with collaborators from Gifu University and other Japanese institutions, developed a compact photonic system using optical microcombs. Their work was published in the peer-reviewed journal Communications Engineering and described in an official Tokushima University announcement.
The result does not mean smartphones can suddenly download files at 112 Gbps. The experiment was an early-stage demonstration focused mainly on the high-capacity wireless connections that could link future 6G base stations with core networks.
The System Reached 112 Gbps at 560 GHz
The researchers transmitted data using a 560 GHz carrier frequency, which sits deep within the terahertz portion of the electromagnetic spectrum.
They achieved 84 Gbps using quadrature phase-shift keying, commonly known as QPSK. By switching to the more data-efficient 16QAM modulation format, the system reached 112 Gbps.
The full technical findings are available in the researchers’ published paper, which describes the result as the first demonstration of 100 Gbps-class wireless transmission beyond 420 GHz.
At 112 Gbps, the experimental connection could theoretically transfer approximately 14 gigabytes of data every second under ideal conditions. A 100GB collection of files could therefore move in a matter of seconds, although real consumer networks would experience overhead, congestion and other limitations.
The headline speed is only one part of the breakthrough. The team also demonstrated that high-frequency wireless signals could remain stable enough to carry advanced modulation at a frequency where conventional electronics face serious technical limits.
Why Researchers Are Moving Toward Terahertz Frequencies
Every wireless generation requires access to sufficient radio spectrum.
Lower-frequency bands provide useful range and can pass through buildings more effectively, but they contain limited bandwidth and are already heavily used by mobile networks, television, Wi-Fi, satellite systems and other services.
Higher frequencies offer much wider channels. Wider channels can carry more information, which makes them attractive for future networks requiring enormous data capacity.
Current 5G systems already use some millimeter-wave frequencies, but researchers expect parts of 6G to expand further into sub-terahertz and terahertz bands. Tokushima University says future 6G systems, expected in the 2030s, may use carriers above 300 GHz to support ultra-high speeds, low latency, massive connectivity and integrated sensing.
The problem is that higher-frequency signals become increasingly difficult to generate, transmit and receive.
Above approximately 350 GHz, conventional electronic signal generators experience declining power and rising phase noise. Atmospheric absorption also restricts range, while physical obstacles can block these signals more easily than lower-frequency transmissions.
Japan’s latest experiment addresses the signal-generation challenge, but it does not eliminate every obstacle facing practical terahertz networks.
Optical Microcombs Made the Breakthrough Possible
The central technology in the system is an optical microcomb.
A microcomb generates many precisely spaced frequencies of light, resembling the evenly arranged teeth of a comb. These optical frequencies can provide highly stable references for creating extremely high-frequency wireless carriers.
Instead of attempting to produce a clean 560 GHz signal entirely through traditional electronic circuits, the researchers used photonics. Two stable optical signals were generated and combined through a process called photomixing, producing the terahertz carrier used for the wireless transmission.
The team directly bonded an optical fibre to a silicon-nitride microresonator. According to the official research summary, this removed the need for the delicate optical alignment normally required by larger laboratory systems.
That change improved stability and made the transmitter dramatically smaller.
The device measured about five millimetres across, compared with approximately 450 millimetres for a more conventional microcomb setup. In other words, the new arrangement was around 90 times smaller in one key dimension.
Miniaturisation matters because a laboratory system that requires constant manual alignment cannot easily become commercial telecommunications equipment.
This Is Mainly a Backhaul Breakthrough
The technology is not primarily intended to connect an individual smartphone directly to a distant mobile tower.
Its most realistic early use may be wireless backhaul.
Backhaul refers to the high-capacity connections carrying data between mobile base stations and the wider internet or core telecommunications network. These connections are often provided by fibre-optic cables, but installing fibre can be expensive, slow or impractical in some locations.
An ultra-fast terahertz link could potentially connect nearby towers, buildings, data centres or network nodes without requiring new underground fibre.
The researchers specifically described the system as a foundation for ultra-high-speed mobile backhaul and photonic-wireless integrated networks. Their published research suggests that compact microcomb-based transmitters could eventually provide more than 100 Gbps through point-to-point wireless links.
That distinction is important. A 112 Gbps laboratory backhaul link does not mean every future 6G phone will receive the same speed.
Consumer performance would depend on distance, network traffic, available spectrum, device hardware, weather, obstacles and how many users share the connection.
The Signal’s Range Remains a Major Challenge
Terahertz waves can carry huge amounts of data, but their practical range is limited.
The higher the frequency, the more easily signals can be weakened by atmospheric gases, rain, walls and other physical objects. Terahertz systems may therefore require highly directional antennas and clear lines of sight.
Future networks could use these links between fixed locations, where antennas can be carefully aligned. Supporting ordinary mobile users moving through buildings, streets and vehicles would be considerably harder.
The research team has not presented the experiment as a finished commercial product. Future work will focus on increasing output power, extending transmission distance, improving antenna design and reducing phase noise further.
The peer-reviewed study summary also notes that higher-order modulation could increase data rates, provided the system maintains sufficient signal quality.
These engineering challenges explain why 6G remains several years away despite impressive laboratory demonstrations.
The Breakthrough Builds on Earlier Japanese 6G Tests
Japan has already demonstrated 100 Gbps transmission at lower sub-terahertz frequencies.
In 2024, NTT DOCOMO, NTT, NEC and Fujitsu announced a system capable of reaching 100 Gbps using the 100 GHz and 300 GHz bands. The companies tested the technology indoors and outdoors as part of Japan’s broader 6G research programme. The official NTT announcement described it as an important step toward practical sub-terahertz communications.
The newer Tokushima University result pushes beyond that work by reaching 112 Gbps at 560 GHz.
Moving above 420 GHz matters because it opens a much higher and less congested part of the spectrum. It also proves that compact photonic equipment can maintain sufficient stability to use advanced modulation there.
The two achievements address different pieces of the same problem. The earlier test demonstrated high-speed transmission over practical distances in lower-frequency bands, while the new research shows that even higher frequencies can support 100 Gbps-class data rates.
6G Will Not Be Defined by Speed Alone
The public discussion around 6G often focuses on maximum download speeds, but future networks are expected to involve much more.
Researchers anticipate 6G could integrate communications with environmental sensing, positioning, artificial intelligence and distributed computing. Networks may support real-time industrial automation, digital twins, autonomous systems and highly immersive extended-reality services.
Extremely fast backhaul would also be useful for connecting dense groups of base stations and moving data between edge-computing facilities.
The 6G broadband connectivity white paper describes a future network combining terrestrial and satellite systems, advanced antenna technologies and high-frequency links capable of supporting peak rates approaching one terabit per second in specialised conditions.
Those figures are targets rather than guaranteed consumer speeds.
Just as 5G users rarely experience the technology’s theoretical maximum, practical 6G speeds will depend on network deployment and real-world conditions.
Commercial 6G Is Still Years Away
The latest demonstration is a research milestone, not a commercial launch.
6G standards have not yet been fully defined, and telecommunications companies still need internationally agreed spectrum rules, hardware specifications and network architectures.
Commercial deployment is generally expected around 2030 or later. Before then, researchers must improve efficiency, range, reliability, manufacturing cost and compatibility with existing infrastructure.
The microcomb approach has potential because it can be manufactured through semiconductor processes and integrated into smaller equipment. However, the receiver, antennas, amplifiers and complete network system must also become practical.
Power consumption will be another critical issue. A network capable of transmitting enormous quantities of data is useful only when it can operate without unreasonable energy requirements.
Why Japan’s 112 Gbps Result Matters
The achievement proves that wireless transmission above 100 Gbps is possible at 560 GHz using a compact and comparatively stable photonic source.
It also provides a potential route around the signal-quality limitations that have restricted previous systems at extremely high frequencies.
The technology is not ready to replace fibre, transform smartphones or deliver nationwide 6G coverage. Its immediate value is scientific and engineering proof that a difficult part of the terahertz spectrum can carry advanced, high-speed data signals.
The next steps will determine whether the system can transmit farther, use less power and operate reliably outside controlled laboratory conditions.
Even with those limitations, Japan’s breakthrough is a meaningful development. It brings high-frequency wireless backhaul closer to practical use and demonstrates that the spectrum needed for future 6G capacity may be technologically accessible.
