Compound Structures of Periodic Holes and Curved Ripples Fabricated by the Interference between the Converging Surface Plasmon Polaritons and Femtosecond Laser

Abstract

Non-cylindrical vectorial femtosecond lasers are employed to irradiate tungsten surfaces. Compound nanopatterns composed of periodic nanoholes and semi-circular curved ripples are produced by scanning the target relative to the laser beam. The tangential direction of the curved ripples is perpendicular to the local polarization direction of the vectorial femtosecond laser beam. Therefore, the formation mechanism of the curved ripples can be attributed to the interference between the incident femtosecond laser and the laser-induced surface plasmon polaritons (SPPs). We found that, in addition to the curved ripples, periodic nanoholes with an average diameter of 406 nm also appeared on the target surface, and they all tended to appear at the vertexes of the semi-circular curved ripples, i.e., the converging point of SPPs. Further experiments demonstrated that the location of the periodic nanoholes was totally determined by the polarization state of the incident femtosecond laser. Therefore, we deduced that the convergent SPPs induced by the non-cylindrical vectorial femtosecond laser interfered with the incident laser at the convergent point, leading to the generation of periodic nanoholes. The investigations in this work exhibited the important role of manipulating the propagation of SPPs in femtosecond laser surface structuring, which not only diversifies the surface patterns that can be produced by laser-induced periodic surface structuring (LIPSS) but also provides deep insights in the excitation and propagation dynamics of SPPs.

Noble-Metal Nanoparticle-Embedded Silicon Nanogratings via Single-Step Laser-Induced Periodic Surface Structuring

“…Scanning the Si surface with such a beam along a linear trajectory allows for a nanotextured surface track to be produced with 70 nm period with an orientation gradually rotating by 90 • when moving from the center of the track towards its periphery (Figure 3f). Such modality allows for the creation of grating-type structures with isotropic properties since ordinary nanogratings with linear arrangement of the trenches expectedly exhibit anisotropic optical behavior [65][66][67][68]. The experiments with structured laser beams also clearly demonstrate that the beam shaping modality allows for the diversity of surface morphologies that can be produced via straightforward fs-laser patterning to be expanded.…”