From the cosy corners of neighbourhood libraries where students connect their laptops to the wifi network to the remote outposts in the Antarctic where scientists monitor weather, wireless communication is the hero of our connected world.

While we marvel at the speed of our current networks, researchers worldwide are already looking beyond 5G to shape the future of communication in 6G networks. You can imagine a world where instant communication powers virtual reality experiences or enables surgeons to control robots from miles away.

To turn these dreams into reality, researchers need wireless channels with ultra-high data speeds, and a recent study published in IEICE Electronics Express unveils a promising breakthrough using lasers to achieve just that. 

A team of researchers from Osaka University and IMRA AMERICA has shattered records by harnessing the power of lasers to enhance data transmission speeds. The trick lies in reducing system noise, a feat achieved by utilising photonics in a sub-terahertz band ranging from 100GHz to 300GHz. 

Ultra-low noise photonics-based sub-terahertz wireless communication system. Image: Osaka University

Multi-level signal modulation

For 6G networks to deliver near-instantaneous communication, researchers rely on a sophisticated technique known as 'multi-level signal modulation'. This method allows for cramming large volumes of data into the sub-terahertz band while maintaining swift response times.

However, operating at the upper echelons of these high frequencies poses a challenge. Multi-level signal modulation is highly sensitive to noise, especially when dealing with precise reference signals. The team led by Keisuke Maekawa found a solution to this bottleneck by leveraging a photonic device-based signal generator. 

Keisuke Maekawa, lead author of the study, said: "This problem has limited 300-GHz communications so far. However, we found that at high frequencies, a signal generator based on a photonic device had much less phase noise than a conventional electrical signal generator."

The researchers utilised a stimulated Brillouin scattering laser, which exploits interactions between sound and light waves, to generate an incredibly precise signal. Implementing this laser-based signal generator in both the transmitter and receiver of a 300 GHz-band wireless communication system, they achieved a single-channel transmission rate of a staggering 240 gigabits per second.

Tadao Nagatsuma, the project's principal investigator, notes that this achievement represents the highest transmission rate ever recorded globally using online digital signal processing (DSP).

As the world continues to embrace 5G technology, researchers are diligently laying the groundwork for 6G. The results of this study mark a significant leap toward realising 300GHz-band wireless communication.

The researchers envision that, with the application of multiplexing techniques and the development of more sensitive receivers, the data rate could skyrocket to one terabit per second. This achievement would usher in a new era of almost instantaneous global communication, transforming how we connect and interact globally.

The study was published in the IEICE Electronics Express journal.