Plasmonic coloring of noble metals by direct laser marking

Functionalization of surfaces with ultrashort pulsed lasers has received fast growing demand from the industry due to the upscaling of laser power available on the market. Nano-scale topographies generated by LIPSS and DLIP allow for controlling of the wetting properties of surfaces as well as optical and tribological surfaces, like super black or low friction surfaces. However, generating and embedding nano particles on metal surfaces has not been exploited, yet for industrial applications. It enables the coloring the surfaces by creating plasmonic resonances. With the proper choice of the laser fluence, number of pulses in a burst and lateral pulse overlap, nano particles of the noble metals like Silver and Gold are created, redeposited on the surface and embedded into a thin layer of melt phase. The control of the size of the NPs and the depth of embedding in the melt pool are the determining parameters for the absorption resonance and therefore the color. Here will present parametric study on the most influencing parameters to correlate the color tones with the NP topographies derived from SEM images.