Optimization of intense laser-driven secondary sources via spectral pulse shaping*

The generation of intense laser-driven high energy particles (>MeV) and X-rays (>keV) from Peta-Watt-class laser interactions with solid targets continues to be a topic of interest. While theoretical and empirical scalings for the production of these sources have been developed, controlling and optimizing laser conversion efficiency into particles and/or X-rays remains challenging. Short pulse shaping (multiple pulses, pulse chirping, or spectral phase shaping) has recently been shown to increase proton maximum energy or hot electron generation, however, studies have been limited to sub-Joule laser pulses in high repetition rate experiments or limited parameter space exploration at high laser energy, low repetition rate facilities.

Here we present results from an experiment performed at the LaserNetUS Scarlet laser facility (5J, 30fs), at the Ohio State University. In this work, we demonstrate modification of charged particle acceleration and X-ray generation through the use of the high order spectral phase components of the laser, tuning the so-called GDD (Group Delay Dispersion) and TOD (Third Order Dispersion) using an acoustic-optic modulator device known as a DAZZLER. Five, on-shot, high repetition-rate laser-plasma diagnostics were deployed to diagnose electron, proton, ion, and X-ray generation. We show trends in production across the examined parameter space and discuss their relevance to applications.