The physics of ultra-short laser interaction with solids at non-relativistic intensities

The interaction of ultra-fast sub-picosecond laser pulses with solids is a very broad area of research. The boundaries for research fields covered by this review are defined as follows. A laser pulse in the context of the review is of ultra-short duration if the pulse is shorter than all major relaxation times. Such pulses excite only electrons, leaving the lattice cold for the time required for the transfer of the absorbed laser energy from the heated electrons to the lattice. For this reason, any laser-induced phase transformations occur in non-equilibrium conditions, making properties of the material drastically different from their equilibrium counterparts. We study laser interaction with matter in a broad range of intensities from those inducing subtle atomic excitations (∼1010 W/cm2) up to high intensity (∼1016 W/cm2), when solid is swiftly transformed into hot and dense plasma. The phenomena emerging in succession in response to increasing laser intensity, namely, the excitations of coherent phonons, phase transitions, ablation, and transformation of material into plasma, are described in consecutive chapters. Two interaction geometries are investigated: the interaction of a laser pulse with a surface, and confined interaction when a laser is focused inside a transparent solid. The highest intensity in all these studies is well below the relativistic limit. Therefore, super-intense laser–matter interactions are beyond the scope in this review. All phenomena involved in laser–matter interaction are considered from the first principles using explicit approximations, eventually aiming to establish the analytical scaling relations, which link the parameters of the laser and the material and allow comparison with experiments. We compare theory to experiments in all intensity ranges. The applications of some studies are described in a separate chapter. The prospects of these studies are indicated in the conclusion.