ИСТИНА

In this paper we present our latest experimental and theoretical results aiming on the optimization of laser pulses parameters (energy, wavelength, polarization) and uncovering new features of femtosecond excitation of solids with mid-IR laser fields. We have investigated the effect of laser wavelength on the plasma formation and laser-induced damage threshold under femtosecond excitation of solids (SiO2, MgF2, ZnSe) tuning the wavelength from visible (0.62 μm) to mid-IR (4.4 μm). For all the samples lowering plasma formation and damage threshold was observed scaling laser driver wavelength to mid-IR. The simulation of the electron plasma density dynamics, via MRE, show that using mid-IR laser pulses with shorter pulse durations leads to significant decreasing of the LIDT threshold that is in excellent agreement with experimental observations. Also we show that the highest deposited energy is reached when the energy of both pulses is close to single color threshold of plasma generation. The use of the second pulse with longer wavelength significantly increases absorbed energy due to more efficient heating of the quasi-free electrons in the conduction band. Elliptical polarization of the long wavelength pulse is additionally increase absorbed energy.