Ultrafast dynamics of laser-excited solids
نویسنده
چکیده
Ultrafast dynamical processes in solids may be triggered, studied and even manipulated with help of ultrashort laser pulses. Also for materials processing there is an enormous potential of ultrashort laser pulses. Thus, femtosecond laser–solid interaction is of significant interest to the fields of both basic research and industrial applications. Here, I present results of theoretical considerations motivated by this intersection between fundamental physics and technical applications. The time-resolved description of the dynamics of a solid during and after irradiation with an ultrashort laser pulse is a challenging task: On ultrashort time scales the irradiated material passes through highly non–equilibrium states of different kinds. Therefore, the theoretical description of the investigated processes may differ strongly from the classical descriptions valid for equilibrium or steady–state conditions. I focus on the necessary differences in the description of the material response due to the short duration of the exciting laser pulses and compare this with established concepts valid for longer pulses. The basic processes during laser ablation with laser pulses of moderate intensities in the region of the ablation threshold, such as excitation, melting and material removal are temporally separated when femtosecond laser pulses are applied, allowing a separate investigation of each of them. Fig. 1 shows a schematic view of the typical time
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