Multiple micro-explosions driven by a single focused femtosecond pulse in transparent material

Darkening and micro-explosions inside ZBaF15 optical glass are investigated by using focused femtosecond laser pulse. With loose focusing, multiple micro-explosions occur in fused silica and ZBaF15 optical glass with single femtosecond pulse. The micro-explosions driven in the center of darkening region are observed in ZBaF15 optical glass. A numerical simulation is given by a model based on the beam propagation in wave-guide channeling induced by the front of excitation pulse. The mechanism of refractive index modification, which induced by femtosecond pulse, is discussed.