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

Tingyuan Wang,Nan Zhang,Lie Lin

doi:10.3390/app12052543

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.

Highlights

IntroductionAccepted: 24 February 2022The generation of femtosecond laser-induced periodic surface structures (fs-laser-induced periodic surface structuring (LIPSS))is a high-throughput, parallel surface-structuring method with subwavelength or deepsubwavelength resolution [1–7]
Accepted: 24 February 2022The generation of femtosecond laser-induced periodic surface structuresis a high-throughput, parallel surface-structuring method with subwavelength or deepsubwavelength resolution [1–7]
The investigations in this work exhibited the important role of manipulating the propagation of surface plasmon polaritons (SPPs) in femtosecond laser surface structuring, which diversifies the surface patterns that can be produced by laser-induced periodic surface structuring (LIPSS) and provides deep insights in the excitation and propagation dynamics of SPPs

Summary

Introduction

Accepted: 24 February 2022The generation of femtosecond laser-induced periodic surface structures (fs-LIPSS)is a high-throughput, parallel surface-structuring method with subwavelength or deepsubwavelength resolution [1–7]. The generation of femtosecond laser-induced periodic surface structures (fs-LIPSS). The modified surfaces with LIPSS patterns have important applications in the fields of structural color [8–11], super-hydrophobicity [12,13], self-cleaning [12,14], and anti-bacterial [15,16], among others. One commonly accepted formation mechanism of fs-LIPSSs is the interference between the incident femtosecond laser and the laser-induced surface plasmon polaritons (SPPs) [17–19]. Compared with the scalar femtosecond laser, the vectorial femtosecond laser can locally manipulate the propagation direction of SPPs and produce more versatile surface patterns [20–28]. The employment of the vectorial femtosecond laser to produce LIPSSs on a target surface is an effective method used to investigate the unique excitation/propagation modes of SPPs by freezing the SPPs into the surface patterns. A non-cylindrical femtosecond vector beam was generated by two phase gratings used correspondingly as the beam splitter and combiner.

Methods

Results

Conclusion