Length control of metal particles containing trajectories generated by metal sphere movement and elucidation of the relationship between metal sphere speed and metal addiction

High-intensity laser-irradiated metal spheres in glass move toward a light source while leaving the doping metal in their trajectories. A method for controlling the trajectory length, which can be used to produce new optical devices in glass, has not been proposed yet. In-situ observations clarified the relationship, wherein the trajectory length increased with the increasing laser power and irradiation duration; the maximum and minimum being 2.0 and 0.1 mm, respectively. Microscopic observations, elemental analysis, and counting the number of metal particles revealed that the maximum speed metal sphere generated the most metal-containing area with the highest number of metal particles.