Researchers at EPFL have developed a nanodevice that operates more than 10 times faster than
today’s fastest transistors, and about 100 times faster than the transistors you have
on your computers.
This new device enables the generation of high-power terahertz waves.
These waves, which are notoriously difficult to produce, are useful in a rich variety of
applications ranging from imaging and sensing to high-speed wireless communications.
The high-power picosecond operation of these device also hold immense promise to some advanced
medical treatment techniques such as cancer therapy.
The team’s pioneering compact source, described in the journal Nature, paves the way for untold
new applications.
Terahertz (THz) waves fall between microwave and infrared radiation in the electromagnetic
spectrum, oscillating at frequencies of between 100 billion and 30 trillion cycles per second.
These waves are prized for their distinctive properties: they can penetrate paper, clothing,
wood and walls, as well as detect air pollution.
THz sources could revolutionize security and medical imaging systems.
What’s more, their ability to carry vast quantities of data could hold the key to faster
wireless communications.
THz waves are a type of non-ionizing radiation, meaning they pose no risk to human health.
The technology is already used in some airports to scan passengers and detect dangerous objects
and substances.
Despite holding great promise, THz waves are not widely used because they are costly and
cumbersome to generate.
But new technology developed by researchers at EPFL could change all that.
The research team built a nanodevice that can generate extremely high-power signals
in just a few picoseconds, or one trillionth of a second, – which produces high-power
THz waves.
The technology, which can be mounted on a chip or a flexible medium, could one day be
installed in smartphones and other hand-held devices.
The compact, inexpensive, fully electric nanodevice generates high-intensity waves from a tiny
source in next to no time.
It works by producing a powerful “spark,” with the voltage spiking from 10 V (or lower)
to 100 V in the range of a picosecond.
The device is capable of generating this spark almost continuously, meaning it can emit up
to 50 million signals every second.
When hooked up to antennas, the system can produce and radiate high-power THz waves.
The device consists of two metal plates situated very close together, down to 20 nanometers
apart.
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 that produces
high-frequency waves.
Conventional electronic devices are only capable of switching at speeds of up to one volt per
picosecond – too slow to produce high-power THz waves.
The new nanodevice, which can be more than ten times faster, can generate both high-energy
and high-frequency pulses.
Normally, it’s impossible to achieve high values for both variables.
High-frequency semiconductor devices are nanoscale in size.
They can only cope with a few volts before breaking out.
High-power devices, meanwhile, are too big and slow to generate terahertz waves.
EPFL's solution was to revisit the old field of plasma with state-of-the-art nanoscale
fabrication techniques to propose a new device to get around those constraints .
The technology could have wide-ranging applications beyond generating THz waves.