Sequential color change on copper surfaces via micro/nano structure modification induced by a picosecond laser

A surface micro/nano structuring technique was demonstrated for colorizing metal surfaces with a picosecond laser. Sequential color change from black to pink was realized on copper surfaces by simply changing the ps laser scanning speeds. Systematic analyses on the spectral response and microstructure characteristics were reported. The spectrum shifting effect corresponding to color change was explained through the surface plasmon resonance mechanism. The current research shows that a high power and high repetition rate ps laser is capable of structuring metal surfaces with a speed up to several meters per second, presenting an efficient and affordable candidate for practical industrial applications.