Multi-pulse agglomeration effects on ultrashort pulsed direct laser interference patterning of Cu

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Surface functionalization by biomimetic patterns in the micro- and nanometer scale is well-established in a wide range of applications. The finely tuned surface properties are directly related to both primary and sub-pattern morphology of the applied topographies, which must be well-adjusted for maximum functionalization efficiency. In this light, the role of proceeding surface modification and its effect on pattern formation alongside multi-pulse ultrashort pulsed direct laser interference patterning (USP-DLIP) of Cu are investigated in detail by applying a multi-method characterization approach. It was shown that aside of topographical remodeling, USP-DLIP processing parallelly affects chemistry and the mechanical deformation state of the substrate surface, which in turn considerably influences laser/material interaction via incubation. An in-depth investigation of the individual and combined impacts of these substrate alterations on localized optical absorptance reveals how primary and sub-pattern formation dynamically respond to process induced surface modification. The DLIP-specific incubation impact on pattern morphology increases with inverted relation to pattern scale. The findings of this study provide a profound insight in the predominant physical interactions involved in pattern formation arising from the mutual influence between laser irradiation and substrate modification during USP-DLIP-processing of Cu allowing for high precision micro- and nanometer scaled pattern design.