Speaker
Description
Ultra-short laser pulses are essential to resolve femtosecond-timescale dynamics in plasma-based particle accelerators. Presented here is a high-intensity hollow-core beam line designed to spectrally broaden an input spectrum by a factor three, with an output pulse energy of ~2 mJ. These pulses can then be compressed to ~10 fs and will be utilized to take crisp shadowgrams of plasma wave sub-structures in LWFAs and PWFAs and furthermore used as a photocathode injector laser in a PWFA.
The spectral broadening is based on the mechanism of self-phase modulation, which requires an intense, short laser pulse and a material with strong third-order nonlinearity.
Noble gases, with their comparatively high ionization levels and sufficiently large nonlinear refractive indices, are top candidates to act as nonlinear medium.
The required intensity for self-phase modulation is achieved by focusing the laser down to a smaller beam diameter.
A hollow-core fiber is used to maintain the small beam diameter over a longer distance and to clean the spatial profile of the pulse.
Challenges in designing such a hollow-core fiber beam line are spatial limitations, ionization de-focusing, laser induced damages on optics and self-focusing effects due to the high pulse intensity.
