Formation of long- and short-periodic nanoripples on stainless steel irradiated by femtosecond laser pulses

In this paper, we report the formation of long-periodic (LP) ripples with a period of 530–600 nm and short-periodic (SP) ripples with a period of 260–320 nm on stainless steel irradiated by 800 nm femtosecond laser pulses. The split of LP ripples plays the decisive role in the formation of SP ripples. We further conduct pump-probe experiments and numerical simulations to study the ultrafast dynamics of the formation of surface periodic ripples.