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Microcombs unlock 112 Gbps wireless link at 560 GHz for 6G

Researchers at Tokushima University have demonstrated single-channel wireless transmission at 112 Gbps in the 560 GHz band using soliton microcombs, marking a significant step toward next-generation 6G communications.

Scientists have pushed wireless speed into territory that current mobile networks can’t touch. A Tokushima University team demonstrated a 112Gbps wireless connection in the 560GHz band, using soliton microcombs to generate a more stable terahertz signal for future 6G systems.

The near-term prize isn’t a faster handset. It’s the hidden infrastructure that carries traffic between network sites, where backhaul capacity can decide whether future 6G speeds feel real or get trapped behind crowded network pipes. That makes this a useful 6G speed breakthrough to watch, even if consumers won’t see it on a spec sheet anytime soon.

Conventional electronic technologies face fundamental limitations in generating stable high-frequency signals beyond 350 GHz, including reduced output power and increased phase noise. These challenges have hindered the realization of ultra-high-speed wireless communication in the terahertz regime, which is expected to play a key role in future 6G systems.

The 560GHz band gives the 112Gbps result its edge. The team sent a single-channel wireless signal well beyond the range where conventional electronic hardware starts running into weaker output power and higher signal noise.

That frequency range sits in the terahertz zone, which researchers are exploring as a way to open wider data lanes for 6G. Earlier communication systems at these frequencies have often stayed in the range of a few to several dozen gigabits per second. This test crossed the 100Gbps class beyond 420GHz, which pushes the work into a more serious category.

At these frequencies, raw speed depends on control as much as bandwidth. Phase noise and limited output power make wireless transmission harder to keep stable, especially when a system is trying to move more data through one channel without the signal falling apart.

Tokushima University’s system uses a compact fiber-coupled microresonator, which reduces the need for precise optical alignment. It also includes temperature control to make the optical resonance behavior more repeatable. Those details sound incremental, but they’re the kind of engineering work that separates a flashy lab number from something that can eventually run for longer periods.

No one should read this as a phone upgrade arriving soon. The researchers still need to cut phase noise further, support higher-order modulation, improve terahertz output power, and extend transmission distance with better antenna design.

The first useful home for the technology will probably be mobile backhaul or photonic-wireless network links. That’s less visible than a new 6G phone, but it’s more important to the network itself. Before 6G can deliver massive speeds to everyday devices, the infrastructure behind those devices needs a faster way to move data around.

Microcomb system tackles key hurdles...To overcome these challenges, the research team developed a microcomb-driven terahertz wireless communication system that combines fiber-coupled microcombs with high-order modulation techniques. The system leverages the high frequency stability and low phase noise of microcombs to generate a low-noise terahertz carrier.

This enabled wireless transmission at 112 Gbps in the 560 GHz band, significantly exceeding conventional terahertz communication systems at these frequencies, typically limited to data rates of a few to several tens of gigabits per second, and demonstrating for the first time 100 Gbps-class wireless communication beyond 420 GHz, opening a new frontier in high-frequency wireless technologies. The research is published in Communications Engineering.

Compact design boosts stability and power...The system is based on a compact and stable microcomb device using a fiber-coupled microresonator. By directly bonding an optical fiber to a silicon nitride microresonator, the researchers eliminated the need for precise optical alignment, enabling significant miniaturization and improved operational stability. This configuration also allowed high-power optical pumping and long-term stable operation, establishing a platform for low-noise terahertz signal generation.

In addition, the integration of a temperature control function for the microresonator improves the reproducibility of optical resonance characteristics and enhances robustness against environmental temperature fluctuations.

High-speed transmission and future directions...In the wireless transmission experiment, two highly stable optical carriers were generated via optical injection locking of the microcomb and modulated using QPSK and 16QAM formats. These signals were converted into a 560 GHz terahertz wave through photomixing and transmitted wirelessly. At the receiver, the signals were recovered using heterodyne detection with a sub-harmonic mixer. As a result, data rates of 84 Gbps (QPSK) and 112 Gbps (16QAM) were achieved.

"This result represents a major step toward practical 6G wireless systems and ultra-high-speed mobile backhaul," said Prof. Takeshi Yasui of Tokushima University.

This work establishes a key technological foundation for ultra-high-speed mobile backhaul links and photonic–wireless integrated networks in 6G systems. Future work will focus on further reducing phase noise, enabling higher-order modulation formats, and extending transmission distance through improved terahertz output power and antenna design.

Provided by Tokushima University