HHG source developments and applications
The topic of High Harmonics Generation is mostly divided into two parts; the development of this femtosecond source in XUV (from 260 nm to 10 nm) and its using for various applications. They represent each of them 50% of time dedicated during beamtime and can serve to each other. For instance, sources with new properties can allow to perform new applications and in reverse in order to perform some applications we push the development of the source in some particular directions.
First, the development of sources is a long standing activity started from the 80’s. But still today major discovers occur. In our group, we study harmonics generated from noble gases by focusing an intense femtosecond laser. Harmonics from low orders in UV to high orders from VUV to XUV are delivered. To optimize properties and the intensity signal of harmonics, we play on the number of laser beams, their wavelengths, their polarization types, the types of gases and even recently magnets have been inserted to affect the generation.
The wide window spectral range allows to study the matter through many different materials. Two major applications are deeply examined; the seeding of free electron lasers and soft X-ray plasma based lasers, and the ultrafast demagnetization of metallic materials through particularly the study of magnetic domains, the xray magnetic circular dichroism and the Faraday effect.