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Subcycle surface electron emission driven by strong-field terahertz waveforms

A collaboration of researchers from Szeged, Budapest and Pécs has led to the development of a completely new electron source driven by high wavelength light, which could provide the basis for the operation of new types of electronic devices in the near future.


Subcycle surface electron emission driven by strong-field terahertz waveforms

 Illustration: Fülöp Sámuel Sihombing

The photoelectric effect (electron emission) is usually produced with the help of ultraviolet or soft X-ray radiation with wavelengths much shorter than visible light. Under such irradiation, the smallest amount of energy allowed by the laws of quantum mechanics is sufficient to free electrons in atoms and molecules. The situation is quite different with radiation at wavelengths much longer than visible light, at wavelengths in the millimetre range, i.e. terahertz radiation: only terahertz radiation with an extremely strong electric field can free electrons from matter through the so-called tunnelling effect.

In a recent paper published in the prestigious journal Nature Communications (https://doi.org/10.1038/s41467-023-42316-0), researchers from ELI ALPS, the Wigner Research Centre for Physics and the University of Pécs investigated this phenomenon. In their experiment, they produced extremely strong electric fields of more than 100,000 V/cm in the form of terahertz pulses. They were the first to experimentally detect surface electron emission induced by terahertz pulses and were also able to control the number of electrons released by reversing the direction of the electric field.

The speed of switching in electronic devices and that of data transmission in telecommunication networks has been increasing steadily for decades. As the new results allow for the construction of high-speed switches operating at terahertz frequencies, these experiments are an important step towards the development of high-field terahertz technology. In our fastest devices, microwaves are expected to be replaced by terahertz waves already in the near future. These experiments also represent a major milestone in the development of small-scale, intense electron sources based on surface electron emission, which are essential in many areas of medicine, biology and materials science.

 

Original publication:

Subcycle surface electron emission driven by strong-field terahertz waveforms

Shaoxian Li, Ashutosh Sharma, Zsuzsanna Márton, Priyo S. Nugraha, Csaba Lombosi, Zoltán Ollmann, István Márton, Péter Dombi, János Hebling, József A. Fülöp

Nature Communications 14, 6596 (2023)

https://doi.org/10.1038/s41467-023-42316-0

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