Laser-driven radiation sources: towards ultrafast nanodosimetry

Unlike other gating methods, this generates isolated attosecond pulses without the need for spectral filtering, thus preserving the pulse’s intensity and coherence.<br><br>Next, multi-MeV energy protons can be generated via target normal sheath acceleration when a relativistic laser interacts with a thin foil target. This laser-driven source of protons has ultra-short picosecond durations. Unfortunately, they also have broadband energies and large divergences.

This thesis investigates the use of helical coils in generating laser- driven focused, quasi-monoenergetic ion beams. Using an optical streaking method, resulted in the measurement of a proton bunch duration of τFWHM = 26 ± 6 ps and an energy spectrum with a mean energy of E = 7.6 MeV and bandwidth of ∆EFWHM = 0.78 MeV. This represents the shortest directly measured duration of a proton bunch far from the source, offering a novel approach for various applications and providing new insights into ion damage in different materials.<br><br>Finally, the observation of GHz frequency oscillations in LiNbO3 crystals induced by laser-driven radiation was studied.

By driving LiNbO3 with laser-driven radiation, ultrafast refractive index changes were launched that propagate at ∼20% the speed of light. This propagation rotates the polarisation of the incident probe light. Controlling these oscillations resulted in a 60 ps polarisation switch.

This observation paves the way for developing a laser-driven, jitter-free Pockels switch. These findings, collectively enhance our understanding of laser-driven radiation sources. They open exciting new avenues for research and possible technological applications.