Thesis

Recent advances in ultrafast optics and the control of highly nonlinear light–matter interactions now make it possible to generate attosecond light pulses (1 as = 10?¹8 s) through High-Order Harmonic Generation (HHG). This process converts a femtosecond laser pulse into coherent, ultrashort radiation in the extreme ultraviolet (XUV) range (10–150 eV). These unique light sources enable access to electronic dynamics on sub-femtosecond timescales and allow the probing of element-specific transitions that were previously only achievable at large-scale facilities such as synchrotrons. The Attophysics Group at LIDYL, a pioneer in the generation, characterization, and application of attosecond pulses, has recently developed sources driven by beams carrying spin (SAM) or orbital (OAM) angular momentum, opening new avenues for studying chiral and magnetic dynamics. Building on these advances, this PhD project aims to synthesize light fields with time- and space-dependent chirality, exploiting in particular the often-neglected longitudinal component of the electric field. Three regimes will be explored: a linear regime (XUV/IR pump–probe), a strongly nonlinear regime (structured visible–IR fields in chiral samples), and a weakly nonlinear regime (IR pump/XUV probe). This work will open a new class of attosecond physics experiments, bridging fundamental exploration and emerging applications.
The student will acquire practical knowledge about lasers, in particular femtosecond lasers, and hands on spectrometric techniques of charged particles. They will also study strong field physical processes which form the basis for high harmonic generation. They will become an expert in attosecond physics. The acquisition of analysis skills, computer controlled experiments skills will be encouraged although not required.
Details at https://iramis.cea.fr/lidyl/pisp/150720-2/