A chip-sized, high-speed modulator developed by engineers at Tufts University may pave the way towards filling the "THz gap" that is limiting the development of new and more powerful devices that can transmit data at higher speeds.

Measurements show the modulation cutoff frequency of the new device exceeded 14GHz and has the potential to work above 1THz, according to a paper published in the journal Scientific Reports. By contrast, cellular networks occupy bands that are much lower on the spectrum where the amount of data that can be transmitted is limited.

The device works through the interaction of confined THz waves in a novel slot waveguide with tunable, two-dimensional electron gas, according to the researchers. The prototype device operated within the frequency band of 0.22-0.325THz, which was chosen because it corresponded to available experimental facilities. The researchers say the device would work within other bands as well.

Although there is significant interest in using the THz band of the electromagnetic spectrum, which would enable the wireless transmission of data at speeds significantly faster than conventional technology, the band has been underutilised in part because of a lack of compact, on-chip components, such as modulators, transmitters and receivers.

“This is a very promising device that can operate at terahertz frequencies, is miniaturised using mainstream semiconductor foundry, and is in the same form factor as current communication devices. It’s only one building block, but it could help to start filling the THz gap,” said Sameer Sonkusale, Ph.D., of Nano Lab, Department of Electrical and Computer Engineering, Tufts University, and the paper’s corresponding author.