The "terahertz" frequency range extends from about 100 GHz to 30 THz, i.e. at wavelengths between 0.01 mm and 3 mm. Long unexplored because of the difficulties of their generation, giving the well-known term “terahertz gap”; there is now a various explored way to generate them: plasma, organic crystal, optical rectification, photoconductive antenna.
THz time-domain spectroscopy (THz-TDS), the generation of broad-band electromagnetic radiation by ultra-short laser pulses together with the pump-probe principle method, emerges as a powerful tool for a variety of applications, such as homeland security, non-destructive testing, imaging and drug monitoring. THz also represent a powerful tool in multiple fields of research, such as material or molecular spectroscopy in chemistry and biology or for the study of superconductors in physics. However, all those applications suffer from the low power of terahertz sources. High average power lasers, such as the ones develops in our groups, pave the way to overcome this issue.
In our group, both development of a variety of high-power THz sources and their applications are of strong interest. Thin-disk lasers and high repetition rate laser push the limits of various THz generation technics such as spintronic; organic crystals or optical rectification. Our records in THz powers allow us to tackle applications such as THz imaging. Those high-power THz sources also found their potential in non-linear spectroscopy: a powerful tool to study the collective network of water. Our research works in THz therefore covers applications of daily relevance to fundamental water research.