Elena Arigliani (Politecnico di Milano) - Pecha Kucha LaPlaSS2020

Elena Arigliani (Politecnico di Milano) - Pecha Kucha LaPlaSS2020

Generation of attosecond laser pulses: hollow fiber alignment and toroidal mirror

Ultrashort laser pulses (femto and attosecond) are essential for the investigation of important processes in physics, chemistry, electronics, and biology. The generation of ultrashort high-energy laser pulses is based on the chirped-pulse amplification (CPA) technique. To generate pulses from a few cycles with energies of the order of a few mJ, it is possible to use the hollow fiber that allows selecting the fundamental mode. The present work is divided into two parts; the first describes the experiment for the alignment of a hollow fiber with subsequent analysis of the coupling efficiency between the power of the input beam and that of the outgoing beam from the fiber. The spectra at the output of a gas-filled hollow fiber, a typical configuration for the generation of attosecond XUV pulses, are then presented and briefly discussed. The second part of the work describes the alignment of a toroidal mirror; a tool that is used in XUV ray focusing. Grazing incidence toroidal mirrors can be used for the micro focusing of attosecond XUV pulses, eliminating the presence of aberrations in the output focus. During the activity, a He-Ne laser was used and for the verification of the size and position of the focus, we used a beam profiler which, connected to a computer, through the BeamStar program, provided data useful for our purposes. The alignment of the hollow fiber was possible thanks to the support on which it was mounted, equipped with screws that allowed a micrometric variation of its position along two translational axes. The toroidal mirror has been mounted on a support such as to allow control of its position along translational and rotational axes. The activity was carried out at the ultra-short pulse laboratory in the XUV of the Milan Polytechnic.