Generation of giant half-cycle pulses of terahertz light

Vitaliy Goryashko
Vitaliy Goryashko. Photo: Camilla Thulin.

The Swedish Research Council reached a decision on February 23, 2017 on project grants and starting grants on Natural and Engineering Sciences. The Department of Physics and Astronomy is granted 45.9 million SEK for the period 2016-2020 for in total six project grants and six starting grants. The projects will begin during 2017.

Project description

Vitaliy Goryashko, FREIA, was granted 3 million SEK for the project “Generation of giant half-cycle pulses of terahertz light” from the Swedish Research Council for the period 2017-2020.

Project description

The wavelength range of terahertz light lies between microwaves usually used in mobile communication and infrared light used, for instance, for heating. THz light is emitted, for example, by this page in the same way as optical light is emitted by the Sun (the Sun is thousand times hotter, it emits light with much shorter wavelength). However, THz light produced by this page is so weak that it is of no practical use. In general, for a long time the generation of THz light was very difficult and really powerful sources of such light did not exist. Only ten years ago sources of very strong THz light started to appear and they have been proved to be of great importance for investigating nature. For example, with very strong THz light physicists can switch on and off magnetic properties of some materials very quickly. Another important example of using THz light is the so-called light-induced superconductivity. By shining a strong pulse of THz light one can force a piece of material to manifest features of a superconductor, which is a material having no resistance to a constant current. This discovered phenomenon gives new insight to the physics of superconductivity.

Hence, this project is to develop a novel concept of generation of quasi-half-cycle pulses of THz light with a field strength in the Volt/Ångström range (inter-atomic fields) and with variable polarization. The aims are to build a theoretical basis and perform a proof-of-principle experiment. The concept is based on using the frequency-chirped coherent spontaneous radiation from prebunched electron beams and controlling the slippage between electrons and the radiation field. It is the analog of the mode locking in conventional lasers.