Light field modulation of ejected SiO_2 particles on fused silica surface

The re-deposition of the ejected SiO_2 particles on the substrate during laser-induced damage of fused silica affects the light field modulation and the beam propagation quality. In this paper, the ejected SiO_2 particles were firstly classified based on the experimental results. Then, the modulation resulting from three types of particles, square, round, and triangular was simulated. Meanwhile, the influences of the particle shape, size, position, and laser wavelength on the field modulation were studied. It showed that the field enhancement factor (FEF) has crucial correlations with the particle size, position, and laser wavelength. When the irradiated laser wavelength was 1064 nm, the square particles located on the front surface, the round particles located on the rear surface of the fused silica generated the largest FEF, respectively. The FEF resulted from the round particles was the largest regardless of whether the particles locate on the front or rear surface when the irradiated laser wavelength was 355 nm. The results also showed that no matter what type of particles, they will be easy to induce the surface or bulk damage of fused silica when they are located on the front surface. In contrast, the maximum field modulation appears in the air when the particles are located on the rear surface. It showed that the field modulation was not the main reason to induce rear surface damage of the fused silica. Graphical abstract