Effective time of thermal effect of ultrashort laser pulses on dielectrics

It is shown that for ultrashort laser pulses (10 fs-1 ps) the total time of the thermal effect on a solid depends on the thermal properties of the medium, size and structure of the region under irradiation rather than on the pulse duration. The time of the thermal effect of ultrashort laser pulses amounts to 0.1-10 ns regardless of the pulse duration, which is comparable with the time of the effect of the nanosecond pulses. This fact should be taken into account in a variety of applications, and particularly, when the nonablation regimes are used. Presented are the analytical expressions for calculating the duration of the thermal effect of ultrashort laser pulses on dielectrics both in cases of the surface and bulk absorption.