Ultrafast electron dynamics and energy deposition during IR-visible femtosecond laser ablation of fluorite

Abstract

The action of ultrashort laser pulses on dielectrics leads to the processes of redistribution of the laser pulse energy in the interaction region. The mechanisms of ultrafast energy deposition and the electron dynamics under the action of ultrashort laser pulses determine the type of final structures or elements in the transparent dielectrics. One type of these elements is a birefringent nanogratings formed with an orientation perpendicular to the laser radiation. In this work, laser-induced birefringent structures in calcium fluoride (CaF2) bulk were obtained under the action of tightly-focused laser pulses with durations 0.3-3.8 ps and wavelengths of 515 and 1030 nm. Birefringence in modified region was analyzed using polarization contrast optical microscope with Abrio imaging system.