Modeling ionization dynamics during Bessel beam propagation with a Particle-In-Cell code

Understanding laser-induced plasma formation dynamics is pivotal for controlling the energy density deposited within the solid dielectrics during ultrafast laser material processing. Conventional numerical codes, however, fail to reproduce the propagation dynamics of tightly focused Bessel beams, which are widely used for stealth dicing. We adapted the massively parallel Particle-In-Cell (PIC) code EPOCH, incorporating background permittivity and Keldysh field- and impact-ionization modules. We compare numerical simulations to experimental results across various imaging diagnostics. Our simulations enabled the identification of the pivotal processes governing dense plasma formation and reproduced the high energy density experimentally observed.