Cascading shocks and heated electrons probability distributions on the surface and inside silicon target irradiated by femto-second laser pulse

Abstract

The femtosecond laser effects on shock cascades at the surface as well as inside the silicon target are studied by using the two temperature method (TTM) for simulating the non-equilibrium system. The laser wavelength is varied from 500 to 1500 nm and significant modifications are noted in the shock cascades, an electron temperature probability distributions, cumulative probability distributions, and electron-lattice equilibration temperature. It is found that the highest and lowest electron temperatures occurred for 500 and 1500 nm lasers respectively. To explain silicon heating sensitivity to the interacting laser wavelength, fundamental parameters including reflection coefficient, absorption, extinction coefficients, refractive index, specific heat, thermal conductivity, electron-hole collision frequency, and lattice-electron coupling coefficient are comprehensively studied. The temperature distributions included non-Gaussian tails and cumulative probability distributions included shock-like jumps at distinctly different temperatures for considered five types of laser wavelengths. The findings of this study can be helpful for understanding silicon crystals interaction with an ultra-short and an intense femtosecond laser pulses.