Computational methods for focused arbitrary laser fields in plasma simulations

An open-source code, arbitrary laser fields for particle-in-cell (ALFP), is provided to enable the use of accurately focused arbitrary beam structures in particle-in-cell (PIC) simulations, and is used to demonstrate the utility of space-time coupled beams for ion acceleration. ALFP provides significant flexibility for simulating focused beams with complex space, time, and polarization couplings in PIC simulations. This facilitates exploration of laser–matter interactions beyond the standard Gaussian laser pulse interaction. Additionally, polychromatic focusing effects that are often left out of analytic formulations are included. ALFP is first verified against theory, both directly with its computed output field and with 3D PIC simulations. Then ALFP is used to simulate space-time coupled beams in laser–matter interaction 2D PIC simulations, revealing improvements in ion collimation.