Contrasted behavior of ripple morphology evolution on metals irradiated with temporally shaped femtosecond laser pulse

Morphological evolution of ripple on nickel surface induced by temporally shaped femtosecond laser irradiation were studied and compared with titanium. It was revealed that the transformation of single-pulse irradiation into double-pulse irradiation can exert very different influence on ripple morphology evolution for different metals. For nickel, the double-pulse irradiation resulted in the growth in rippled area, ripple period and ripple contrast, compared with the single-pulse irradiation, while double-pulse processing of titanium leads to reductions in in rippled area and ripple period. The contrasted influence of Te on electron-phonon coupling factor (G) for the two metals was the primary factor for the different behaviors of ripple morphology evolution with temporal pulse shaping.