ABSTRACT

Abstract. The optical breakdown thresholds (OBTs) of dielectric and semiconductor were measuring using both single and double 40-fs laser pulses with various energies. By measuring the OBTs with different energy and the delay time between two pulses, we found opposite transformation rules for fused silica and silicon. We suggest that the difference is caused by two factors that affect the ablation of the material. One is the energy gap being shrunk due to the electron-hole interaction if electrons are excited from the valence band and another factor is the diffusion of the electron-hole plasma.