Transfer of orbital angular momentum in high-harmonic generation

• Applicant: Professor Dr. Stephan Fritzsche
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 440556973

High harmonic generation (HHG) has been found a versatile source of XUV radiation. Today, the generated harmonics as well as the derived attosecond pulses can be produced and tailored quite routinely in their polarization by shaping the driving laser beam. Moreover, high-order harmonics can be also generated with twisted light fields, and where the orbital angular momentum of the driving beam is transferred to the generated XUV radiation, owing to the conservation of orbital angular momentum. In most of these (theoretical) studies, however, some idealized driving fields were assumed. This either includes perfectly linearly- or circularly-polarized driving beams, for which the spin and orbital angular momentum can be treated independently. Less attention has been paid so far to the HHG with short twisted pulses. In this research project, we shall explore how different distortions in (the symmetry of) the laser field affect the HHG with twisted light, as for two-color elliptical or ultrashort driving pulses. Moreover, emphasis will be placed on non-paraxial twisted beams, such a Bessel beams, in order to better understand the coupling of spin and orbital angular momentum upon the HHG process. Both, the strong-field approximation as well as numerical solutions to the Maxwell equation will be utilized in order to compute the emission and propagation of harmonic radiation.

• DFG Programme: Research Grants