Micro/nano fabrication of periodic hierarchical structures by multi-pulsed laser interference structuring

Micro/nano fabrication of periodic surface structures by Laser interference metallurgy, which showed fabricating high-resolution features on large-area metallic substrates by interfering laser beams was investigated. Laser induced periodical surface structure (LIPSS) gave the possibility of fabricating spatially periodic structures in the sub-micrometer scale and was first observed upon irradiation of semiconductor surfaces by Ruby laser pulses. The period of the observed structure was close to the wavelength of the incident radiation, and the ripples were oriented perpendicular to the direction of the laser polarization. SEM micrograph of the sample surface irradiated with one laser beam, 408 mJ/cm2 of laser fluence, and 20 laser pulses. Experimental results indicate that the periodic surface structure extended over large areas appeared only after several consecutive laser pulses and the nano-ripples are perpendicular to the electric field.