Ultra-short pulse laser-induced damage in transparent materials

A theoretical model based on solid state energy band theory and energy conservation is developed which can describe temporal and spatial distribution of carriers in nonmetal materials during laser-induced damage.The relation between damage threshold,ablation depth and laser pulse duration,wavelength,energy fluence is studied with the model.The effects of the electronic properties of material on damage threshold and ablation depth are also discussed.The respective roles of multi-photon ionization,tunnel ionization,and avalanche ionization in laser induced damage are examined,and it is found that photo-ionization is always the most important role in the nonmetal materials during ultra-short laser induced damage.