Multiple micro-explosions induced by a single focused femtosecond pulse in glass

Color-center and micro-explosions are generated in ZBaF15 optical glass by using focused near-IR femtosecond laser pulse with different incident energy. And multiple-explosions are induced in fused silica. The experiments show that the micro-explosions driven in the center of color-center region are observed in ZBaF15 optical glass with high incident energy. With loose focusing, multiple micro-explosions occur in fused silica and ZBaF15 optical glass with a single femtosecond pulse. Based on the self-focusing effect and free-electron plasma defocusing effect induced by femtosecond laser pulse in transparent material, multiple-micro explosions are analyzed in theory. At the same time, the mechanism of refractive index modification, which induced by femtosecond pulse, is discussed too.