Design Changes to a Laser-Plasma Simulation Code to Permit Twisted Light Studies

Abstract

Schemes to implement laser bandwidth wide enough to mitigate laser-plasma instabilities will be both intrusive and expensive. As an alternate approach, work is presented that investigates the mitigating effects of spatial, rather than temporal, laser beam conditioning on cross-beam energy transfer (CBET) [I.V. Igumenshchev et al., Phys. Plasmas 19, 056314 (2012)]. Such conditioning might be generated by phase plates alone and could therefore be implemented more easily. We have quantified the energy exchange occurring between crossing laser beams that possess orbital angular momentum (OAM) as the amount of OAM exchange between the beams is varied [cf. e.g., M. Padgett et al., Physics Today 57, 35 (2004)]. This work enables studies to be performed in 3-D using the non-paraxial wave-based LPSE simulation code [J.F. Myatt et al., J. Comp. Phys 399, 108916 (2019)]. It required significant modifications to the code to allow for the beams with OAM. The modifications required changes to the boundary conditions and the total field scattered field (TF-SF) to be implemented successfully