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 (FWHM) duration of about 80 fs. These pulses are delivered at wavelength λ = 800 nm by a solid-state laser pumped Ti:Al ₂ O ₃ 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.