High-power terahertz waves from a CMOS-compatible device

March 26, 2020 // By Julien Happich
A type of non-ionizing radiation (safe to use), terahertz (THz) waves can penetrate paper, clothing, wood and walls, as well as detect air pollution, making them suitable for numerous security and medical imaging applications.

What's more, their ability to carry vast quantities of data could hold the key to faster wireless communications. Hence, academics are racing to design low-cost and compact THz sources to expand their field of applicability beyond the expensive passenger scanning apparatuses found in some airports.

Now, a team of researchers at the Power and Wide-band-gap Electronics Research Laboratory (POWERlab) from Ecole Polytechnique Federale de Lausanne (EPFL) has built a nanodevice capable of generating extremely high-power signals in just a few picoseconds, producing high-power THz waves.

The nanoscale terahertz wave generator can be implemented
on flexible substrates. Credit: EPFL / POWERlab.

The compact and inexpensive device described in the Nature journal under the paper title “Nanoplasma-enabled picosecond switches for ultrafast electronics” consists of two metal plates situated very close to one another, separated by a gap as small as 20nm. When a voltage is applied, electrons surge towards one of the plates, where they form a nanoplasma. Once the voltage reaches a certain threshold, the electrons are emitted almost instantly to the second plate. This rapid movement enabled by such fast switches creates a high-intensity pulse (with a spiking voltage from 10V to 100V) that produces high-frequency waves. In contrast, conventional electronic devices are only capable of switching at speeds of up to one volt per picosecond, too low to produce high-power THz waves.

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