Abstract
A novel femtosecond laser etching and its mechanism of Cu-phthalocyanine solid were investigated by using fs (170 fs) and ns (100 ns) pulses of a 780 nm Ti: Sapphire laser. Above ablation thresholds, the depth etched by fs laser excitation becomes constant and is almost independent of laser fluence, while the depth etched by ns laser excitation increases gradually. We name the unique fs ablation phenomenon “discrete etching”. In order to reveal the evolutions from fs laser excitation to the nm etching, we measured directly excitation energy relaxation and surface morphology change with fs transient absorption spectroscopy and fs surface light scattering imaging, respectively. On the basis of the results, we propose a fs laser ablation model that ultrafast stress increase brings about mechanical disruption leading to the discrete etching behavior.
