The dual mechanism underlying laser excitation of bulk and surface elastic waves in ablative regime

It is usually considered that plasma pressure impulse is the only mechanism corresponding to the laser excitation of bulk and elastic surface waves in an ablative regime. We report the first observation of a dual mechanism where the laser-induced shockwave impacts the target and generates secondary bulk and surface elastic waves some dozens of nanoseconds after the primary ones are generated by the plasma pressure impulse. We propose that the superimposing of the two wave groups can cause addi-tional frequency components that should be considered in research and applications employing elastic waves generated by strong laser ablation.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

It is commonly believed that plasma pressure impulse is the sole mechanism for laser-induced bulk and elastic surface waves. However, we have observed a dual mechanism where the laser-induced shockwave impacts the target, generating secondary bulk and surface elastic waves several tens of nanoseconds after the primary ones caused by the plasma pressure impulse. We suggest that the overlapping of the two wave groups can lead to additional frequency components that should be taken into account in research and applications involving elastic waves generated by strong laser ablation.