Researchers Produce a New Multiplexer Made from Silicon for Terahertz-range Communications

Researchers from Osaka University in Japan and the University of Adelaide in Australia collaborated to develop a new pure silicon multiplexer for terahertz communications in the 300-GHz band.

“To control the large spectral bandwidth of terahertz waves, a multiplexer, which is used to split and join signals, is critical for dividing the information into manageable chunks that can be more easily processed and thus transmitted faster from one device to another,” said Associate Professor Withawat Withayachumnankul of the University of Adelaide’s School of Electrical and Electronic Engineering.

A new design of ultra-small silicon chip called a multiplexer will effectively manage terahertz waves which are key to the next generation of communications: 6G and beyond.

Until now, compact and practical terahertz multiplexers have not been developed. The new terahertz multiplexers will be extremely useful for ultra-broadband wireless communications because they are inexpensive to produce. “The shape of the chips we designed is critical for combining and splitting channels so that more data can be processed more quickly. Its beauty is in its simplicity.”

People all over the world are increasingly using mobile devices to connect to the internet, and the number of connected devices is growing at an exponential rate. Machines will soon communicate with one another in the Internet of Things, necessitating even more powerful wireless networks capable of transferring large amounts of data quickly.

Terahertz waves are a portion of the electromagnetic spectrum with a raw spectral bandwidth far greater than that of traditional wireless communications, which are based on microwaves. Using a novel optical tunneling process, the team created ultra-compact and efficient terahertz multiplexers.

“A typical four-channel optical multiplexer may cover over 2000 wavelengths. In the 300-GHz band, this would be about two meters long “Dr. Daniel Headland of Osaka University, the study’s lead author, explained. “Our device is only 25 wavelengths across, resulting in a 6000-fold reduction in size.”

Silicon multiplexer chip will drive next generation communications

The new multiplexer covers more than 30 times the total spectrum allocated in Japan for 4G/LTE, the fastest mobile technology currently available, and 5G, the next generation, combined. Because bandwidth is proportional to data rate, the new multiplexer enables ultra-high-speed digital transmission.

Because it allows for the delivery of switched services to small groups of customers, wavelength division multiplexing has become a standard in the engineering of cable television and similar networks. It accomplishes this by allowing the transmission of multiple independent signals over shared fibers and via shared optical amplifiers.

“Our four-channel multiplexer has the potential to support an aggregate data rate of 48 gigabits per second (Gbit/s), which is equivalent to streaming uncompressed 8K ultrahigh definition video in real-time,” said Associate Professor Masayuki Fujita of Osaka University. “We intend to integrate this multiplexer with resonant tunneling diodes to provide compact, multi-channel terahertz transceivers to make the entire system portable.”

The team’s modulation scheme was quite simple; terahertz power was simply switched on and off to transmit binary data. More advanced techniques exist that can squeeze even higher data rates, up to 1 Terabit/s, into a given bandwidth allocation.

“The new multiplexer, like computer chips, can be mass-produced, but it is much simpler. As a result, large-scale market penetration is possible “Professor Tadao Nagatsuma of Osaka University agreed.

“This would enable 6G and beyond applications, as well as the Internet of Things and low-probability-of-interception communications between compact aircraft such as autonomous drones.” This research was published in the journal Optica.