From a New Chip to Broader Ranges—The Push for Terahertz Technology Continues

Lying between the 30-micrometer and 3-millimeter range of the electromagnetic (EM) spectrum, terahertz (THz), or submillimeter wavelength radiation might be closely tied to the development of future generations of telecommunication networks.

Dubbed a candidate technology for 6G, this frequency band has already been proven to be capable of achieving faster data transfer rates when compared to 5G, prompting researchers and engineers to dive further into the science behind generating and reading signals using these wavelengths.

 

Overview of the EM spectrum showing the terahertz band.

 

This article takes a look at three of the most recent developments in terahertz technologies. Two of these breakthroughs come from academia, while one comes from industry. Although it is important to note that terahertz radiation has multiple use cases, today, we will be focusing primarily on implementing this technology for wireless broadband cellular telecommunication networks.

 

Ultra-thin Photonic Circuits for Terahertz Signal Generation

Earlier this year, a team of scientists from EPFL in Switzerland, ETH Zurich, and Harvard University published their findings in the development of proprietary circuitry for the precise generation of terahertz signals. Led by professor Christina Benea-Chelmus from EPFL’s HYLAB, the team manufactured an integrated circuit with potential applications in both optics and telecommunications.

 

The researcher's chip and setup for generating the THz signals. Image used courtesy of EPFL

 

Utilizing the properties of a synthetic chemical called lithium niobate (a compound commonly used in the manufacturing of electronic components and sensors), the researchers were able to create a photonic chip that could not only produce terahertz waves but also allow for the exact control of the frequency, amplitude, and phase of the signal.

This ultra-thin film chip is crafted through an etching process at the nanometer level, where an arrangement of channels called waveguides enables microscopic antennas to broadcast terahertz signals with the help of standard optical fibers.

According to professor Benea-Chelmus, this small device which uses familiar manufacturing methods and traditional optical electronics can be packaged into a miniature embedded component for sending and receiving data which could be a valuable asset in the development of 6G networked devices.

Other use cases include non-destructive spectroscopy and control of quantum objects, although currently, the team’s priority is improving their design’s waveguides and antennas in order to create signals with larger amplitudes and fine-tune their terahertz frequencies even further.

 

Improving the Range of Terahertz Communication

A common rule of thumb for radio data transfer is that the higher the frequency of the signal, the shorter the distance it can travel. If we take a look at the high frequencies that lie in the terahertz range, we would get a maximum distance of about a foot between the transmitter and the receiver before our communication starts exhibiting loss.

A team of scientists from Northeastern University, NASA’s Jet Propulsion Laboratory, and the Air Force Research Laboratory have come up with a novel approach to overcoming these challenges, establishing a multi-gigabit per second connection with a link of over one mile.

 

Researchers have found a way to establish further terahertz connections. Image used courtesy of Matthew Modoono/Northeastern University

 

According to professor Joseph Jornet from Northeastern, the key to their success was a process of removing the mixer (a module traditionally used for adding information to a signal) from their communication channel as it negatively impacted their system due to the high power requirements of transmitting terahertz signals.

This way, to set up a reliable link, the team pre-distorted the information and fed it straight into the source, removing the need for reconstruction at the receiver end, where they would get an almost clean signal out of the gate (still necessary to process).

Behind this process lies an electronics system based on traditional Schottky diodes that can send data wirelessly with the same speed as fiber optics and tested at a range of 2 km. According to professor Jornet, this work can be used in developing a global 6G network that can allow for extremely high wireless internet speeds around the world through satellite communication as opposed to a fiber optics cable infrastructure.

 

Canon Develops a Terahertz Chip

On the industry side of the spectrum, Canon, the Japanese tech conglomerate popular for its camera and printer devices, announced a new compact terahertz semiconductor chip with possible applications in security in the form of imaging as well as telecommunications in the form of 6G.

 

Canon's latest terahertz chip. Image used courtesy of Canon

 

Using components called resonant tunneling diodes, Canon’s engineers were able to shrink its design and create an IC capable of both high output and high detectability while being packaged into a footprint that is much smaller than other demonstrations. These diodes were useful in that they emit terahertz radiation from an antenna that is built into the semiconductor, effectively eliminating the need for modules such as frequency multiplexers, horn antennas, and lenses,

The integrated array of 36 antennas, accurately synchronized with a deviation of no more than one picosecond, allowed for greater accuracy and clarity in signal transmission while also having possible effects on overcoming the range challenges of terahertz technologies.

Currently, this device is intended for use in small electronic devices such as phones and cameras, but also in other computer systems such as real-time active imaging. According to Canon, its new chip can also allow for nonintrusive body scanning and detection of concealed weapons with a range of several meters, appropriate for security uses in heavy pedestrian locations without disrupting the flow of traffic.

 

A Possible Shift From Optics To Wireless?

Although the 5G standard has yet to reach its peak, the advancements in computer and network technologies that rely on increasingly higher data transfer speeds might have to welcome terahertz as the next generation standard sooner rather than later.

While solving the challenges of component size and range, which these three new discoveries have effectively achieved, it becomes important for the industry as well as the standardization institutions to inspect the viability of these technologies. This includes its integration into our telecommunications networks and future generations of consumer electronics, possibly shifting the emphasis from growing the world’s fiber optic infrastructure to creating a widespread broadband wireless 6G network. Overall, terahertz technology looks like a promising futuristic technology.