TITLE:
Thermal response and optical absorptance of metals under femtosecond laser irradiation
AUTHORS:
Anatoliy Y Vorobyev, Chunlei Guo
KEYWORDS:
Femtosecond Laser; Ablation; Residual Energy; Absorptance; Surface Structures
JOURNAL NAME:
Natural Science,
Vol.3 No.6,
June
22,
2011
ABSTRACT: A detailed study on correlation between residual thermal response of a sample and its optical absorptance change due to laser-induced sur-face structural modifications in multi-shot fem-tosecond laser irradiation is performed. Ex-periments reveal an overall enhancement for residual thermal coupling and absorptance in air. Surprisingly, residual thermal coupling in air shows a non-monotonic dependence on pulse number and reaches a minimum value after a certain number of pulses, while these behaviors are not seen in absorptance. In vacuum, how-ever, both suppression and enhancement are seen in residual energy coupling although ab-sorptance is always enhanced. From these ob-servations, it appears that air plasma plays a dominant role in thermal coupling at a relatively low number of applied pulses, while the forma-tion of craters plays a dominant role at a high number of pulses.