Study of the parameters of laser-induced shock waves for laser shock peening of silicon

The ranges of energies of femtosecond laser pulses and distances from the focusing point of intense (up to 10$^{13}$ W/cm$^2$) femtosecond laser radiation to a silicon sample in which phase transitions can be initiated have been determined using the time-resolved shadow photography technique. It has been found that the tight focusing ($NA = 0.5$) of femtosecond near infrared laser radiation provides a pressure of $15$ GPa, which corresponds to a pressure of ($40 \pm 6$) GPa in the case of laser shock peening of silicon and exceeds the threshold value necessary for the initiation of a family of phase transitions ($11$, $14$, and $33$ GPa). The pressure on the front of the shock wave propagating in the medium decreases rapidly (in $2.5$ ns) below this threshold value, which significantly restricts the possible application regimes of laser shock peening.