From there Björn Manuel Hegelich brought that spark to the Max Planck Institute for Quantum Optics in Germany, working with Professors K. Witte, J. Meyer-ter-Vehn and D. Habs. His PhD work focused on laser-driven particle acceleration, using for the first time a new generation of ultra-short pulse lasers based on chirped pulse amplification (CPA) invented by Nobel Prize winners Donna Strickland and Gérard Mourou. CPA made it possible to achieve laser-particle acceleration to high energy.