Wireless link based on photonics breaks speed records for data transmission

From coffee shop patrons connecting their laptops to local Wi-Fi to remote weather monitoring stations in Antarctica, wireless communication is an essential part of modern life. Researchers around the world are currently working on the next evolution of communications networks, called “beyond 5G” or 6G networks.

To enable the near-instantaneous communication needed for applications such as augmented reality or remote control of surgical robots, ultra-high data speeds will be required over wireless channels.

In a study published in IEICE Electronic ExpressResearchers from Osaka University and IMRA AMERICA have found a way to increase these data speeds by reducing noise in the system using lasers.

To store large amounts of data and ensure fast responses, the subterahertz band, which extends from 100 GHz to 300 GHz, will be used by 6G transmitters and receivers. A sophisticated approach called “multi-level signal modulation” is used to further increase the data transmission rate of these wireless links.

However, when operating at the upper end of these extremely high frequencies, the multilevel signal modulation becomes very sensitive to noise.

To work well, it relies on accurate reference signals, and when these signals begin to move forward and backward in time (a phenomenon called “phase noise”), the modulation’s performance multi-level signal drops.

“Until now, this problem has limited communications to 300 GHz,” says Keisuke Maekawa, lead author of the study. “However, we found that at high frequencies, a signal generator based on a photonic device exhibited significantly less phase noise than a conventional electrical signal generator.”

The team used a stimulated Brillouin scattering laser, which uses interactions between sound and light waves, to generate a precise signal. They then implemented a wireless communication system in the 300 GHz band that uses the laser signal generator in the transmitter and receiver. The system also used in-line digital signal processing (DSP) to demodulate receiver signals and increase data throughput.

“Our team achieved a single-channel transmission rate of 240 gigabits per second,” says project manager Tadao Nagatsuma. “This is the highest transmission rate achieved so far worldwide using online DSP.”

As 5G spreads across the world, researchers are working hard to develop the technology that will be needed for 6G, and the results of this study are an important step toward wireless communication in the 300 GHz band.

Researchers predict that with multiplexing techniques (where multiple channels can be used) and more sensitive receivers, the data rate can be increased to 1 terabit per second, paving the way for a new era of global communication almost instantaneous.