The race for 6G wireless data has just achieved a major speed limit. Japanese rsearchers have developed a new microcomb-driven terahertz (THz) wireless communication system that achieves data rates up to 112 Gigabits per second (Gbps) in the 560 GHz band.

This technology overcomes the power and noise limitations of conventional electronics beyond 350 gigahertz (GHz) to establish a foundation for future 6G networks and ultra-high-speed mobile backhaul.

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

Overcoming electronic limitations

Engineers have been actively trying to build the next generation of ultra-fast wireless networks, but have hit a brick wall. To reach the high data speeds promised by 6G, data must travel on ultra-high-frequency terahertz (THz) waves. But conventional electronics simply give up when pushed this hard. 

As frequencies climb past 350 GHz, electronic signals lose power and become flooded with “phase noise” — the digital equivalent of a blinding snowstorm.

Through the integration of advanced photonics and high-order data modulation, the team achieved a historic milestone: the first-ever 100 Gbps-class wireless transmission beyond 420 GHz.

Specifically, they blasted data at 112 Gbps over a 560 GHz carrier wave. That is fast enough to download multiple 4K movies in the blink of an eye, completely dwarfing current experimental systems that struggle to output more than a few gigabits at these extreme frequencies.

How did they do it? The team traded standard electronic circuitry for light.

A technology in this development is a tiny device called an optical microcomb. Microcombs act like high-tech optical rulers, generating a series of perfectly spaced, ultra-stable, sharp lines of laser light.

As these optical lines are so stable, the microcombs exhibit incredibly low phase noise, making them the ideal foundation for pristine terahertz signals.

Light mixing

To make this technology viable for the real world, the researchers had to solve a major hardware headache: optical alignment.

Usually, bouncing lasers into microscopic chips requires agonizingly precise, fragile alignment setups. The slightest vibration can ruin the connection. The Tokushima team solved this by permanently bonding an optical fiber directly onto a silicon nitride microresonator.

This direct-bonding technique accomplished three major feats. It achieved extreme miniaturization by shrinking a bulky lab setup into a compact device, boosting power by enabling high-power optical pumping without alignment drift.

Moreover, the device provided climate-proofing through integrated temperature controls that shield the chip from environmental fluctuations.

“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,” the researchers noted. 

To actually send the data, the team isolated two highly stable optical carrier signals from the microcomb. And coded these light signals using advanced modulation formats — QPSK and 16QAM — which pack more data into every single wave transmission.

The results speak for themselves: the system achieves data rates of 84 Gbps with QPSK modulation and 112 Gbps with 16QAM modulation.

While your smartphone won’t be tapping into 560 GHz frequencies anytime soon, this technology is a massive win for the hidden infrastructure that keeps the internet moving. It is a perfect fit for mobile backhaul — the heavy-duty wireless links that connect cellular towers to the main internet backbone.

Instead of tearing up streets to lay miles of expensive fiber-optic cables, telecom companies could eventually use these microcomb terahertz beams to shoot massive, fiber-like data loads through the air from tower to tower.

Up next, the team plans to squeeze even more data out of the waves by further suppressing phase noise. Also, the plan is to design advanced antennas to boost output power, aiming to push these record-breaking speeds over much longer distances.