High contrast periodic plasma pattern formation during the laser-induced breakdown in transparent dielectric

Abstract

Based on a simple 1D initial-time model, we have carried out the numerical simulation for the spatio-temporal evolution of femtosecond laser pulse induced breakdown in transparent dielectric (fused silica) at the nonlinear stage of the plasma resonance ionization instability. The instability develops from very small seed perturbations of the medium permittivity and results in, because of the strong mutual enhancement of the electric field and plasma density perturbations in the plasma resonance region, the formation of the subwavelength periodic plasma-field structure consisting of the overcritical plasma layers perpendicular to the laser polarization. The calculation of the time-course and spatial profiles of the plasma density, field amplitude, and energy deposition density in the medium during one breakdown pulse has allowed us to establish the main possible scenarios of the process considered and to found the laser intensity range where this process can underlie the nanograting modification of the medium by repeated pulses.