Ultrafast electronic dynamics during femtosecond laser-induced damage in omnidirectional reflector

The omnidirectional reflector SiO₂/TiO₂ is prepared and its threshold fluences and ablation depths at different pulse durations and fluences is studied. In addition a new pump and probe experiment system is developed. The probe pulse is kept as short as possible, while, the pump pulse is stretched and its duration is much longer than that of the probe pulse. Time-resolved excitation processes and damage mechanisms in omnidirectional reflector SiO₂/TiO₂ is studied. A coupled dynamic model, not only considering the excitation of the material by the laser, but also the counteraction of this excitation to the laser, is employed to study the damage mechanisms. This model well explains the excitation processes during the damage of omnidirectional reflector.