Femtosecond laser induced ablation of crystalline silicon upon double beam irradiation

Ultra-short pulsed laser radiation has been shown to be effective for precision materials processing. Advantages include the non-thermal nature of ablation process and short thermal penetration depth. These are ideal characteristics for precision microstructuring and controlled ablation. A crystalline silicon sample is subjected to two optically separated ultra-fast laser pulses of full width half maximum (FWHIM) duration of about 80 fs. These pulses are delivered at wavelength lambda = 800 nm by a solid-state laser pumped Ti:Al2O3 femtosecond oscillator seeding a regenerative amplifier. Femtosecond-resolved imaging pump-and-probe experiments in reflective and Schlieren configurations have been performed to investigate plasma dynamics and shock wave propagation during the sample ablation process. (C) 2002 Elsevier Science B.V. All rights reserved.