Electrodynamic simulation of laser beam propagation in waterjet-guided laser processing

Waterjet-guided material processing is a technique that combines the capabilities of laser material processing with water jetting. In this study, we have investigated laser beam propagation in a waterjet column by numerically solving the Maxwell equations and the heat equation. A 1064 nm laser and its frequency-doubled 532 nm laser were chosen for the simulations, and the finite-difference time-domain (FDTD) method was employed for solving the Maxwell equations. The coupling effect of the laser and waterjet was simulated with different numerical apertures and different waterjet column diameters. Extensive investigations on laser absorption phenomena regarding the outer surface geometries of the waterjet (cylindrical shape with and without sinusoidal perturbation), and temperature distributions were also conducted. To the best of the authors' knowledge, this is the first electrodynamic simulation of laser beam propagation and interaction with a water column in waterjet-guided laser processing. Some interesting findings concerning laser beam absorption characteristics inside a waterjet column were revealed.