![]() The reaction has processes with typical temporal and spatial scales differing by several orders of magnitude, making a complete description of the phenomenon, from material excitation to destruction, a formidable task. The essence of its difficulty lies in the multiscaled nature of the problem. The physics underlying ultrafast laser ablation of materials, however, is undoubtedly difficult. This work serves to highlight the effects of damage incubation on multiple-pulse ablation situations and provides a simple and practical method to predict such morphological characteristics of an arbitrary material. By following the energy absorption characteristics predicted by the latter model, we were able to derive universal relations between ablated depth and incident energy density for sapphire. ![]() ![]() To understand the results, we create a simple empirical model for material energy absorption by characterizing interpulse absorption changes and analytically derive solutions for two limiting cases in which the material has either a very low (quasistatic absorption) or very high (accumulative absorption) damage incubation characteristic. We observe clear evidence of incubation-induced changes in ablation phase and nonlinear dependence of depth on the incident total energy density. Here, in order to quantify the effects of damage incubation in a practical processing setting, we study ablation morphologies of shallow grooves formed on the surface of sapphire ( α -Al 2 O 3 ) with varying laser pulse number and energy in a purpose-made experiment. However, only a few studies have incorporated these effects into multiple-pulse ablation models due to its complexity. ![]() Damage incubation can induce striking changes in the observed morphology during ablation and should be an important factor governing processing results. A factor which particularly complicates ablation situations is “damage incubation,” a phenomenon in which the intrinsic optical properties of the processed material change due to accumulated defects from repeated laser excitation. With the advancement of ultrashort pulsed-laser processing technologies, greater control of processing conditions has come into demand. ![]()
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