Generalized Plasmonic Modelling of the Effect of Refractive Index on Laser-Induced Periodic Nanostructures

A Abdelmalek,E.-H Amara,R Ramponi,S M Eaton,V Bharadwaj,Z Bedrane

doi:10.32732/jma.2019.8.2.73

Abstract

Laser-induced periodic surface structures (LIPSS) have been studied theoretically employing generalized plasmonic modelling on several dielectric materials such as SiO2, Al2O3, ZnO, AlAs and diamond exposed to 800 nm wavelength multi-pulse femtosecond laser irradiation. The study of the optical properties of the materials during laser irradiation reveals a formation of a metallic like pseudo-material on the irradiated layer during excitation. A study of the grating periodicity of the nanostructures shows that the materials having a high refraction index allow LIPSS formation with a wide range of grating periodicities. Results also show High Spatial Frequency LIPSS formation with periodicities 3 to 8 times lower than the laser wavelength.

Highlights

Laser-induced periodic surface structures (LIPSS), called as nanogratings [1] or nanoripples [2] has become a fascinating phenomenon in laser-matter interaction science
This type of LIPSS generally occurs at metal surface or semiconductor with a laser fluence near the ablation threshold, where the interference of the electric field of the Surface Plasmon Polariton (SPP) with the incident laser beam leads to a deposition of spatially modulated energy on the material resulting in a nanostructure formation [4]
Since a pseudo-metal layer is built on the surface of dielectric materials during the irradiation by multipulse fslaser, a generalized plasmonic model can be used to model the formation of nanostructure between pseudo-metal layers and dielectric surrounding medium in various dielectric materials such as SiO2, Al2O3, ZnO, aluminum arsenide (AlAs) and diamond under 800 nm multi-pulse fs-laser irradiation

Summary

Introduction

Laser-induced periodic surface structures (LIPSS), called as nanogratings [1] or nanoripples [2] has become a fascinating phenomenon in laser-matter interaction science. In the second type of LIPSS, a sub-wavelength periodic nanostructure can be observed at dielectric surface during the irradiation by multi-pulse femtosecond laser below the ablation threshold This phenomenon is called High Spatial Frequency LIPSS (HSFL), having a period ΛΛ less than λλ/2 [5]. Miyaji et al [12] showed that a metal-like layer can be formed at the surface of dielectric materials during the irradiation by multi-pulse fslaser due to disordering (non-thermal melting) [8] They have shown that the excitation of SPP is the dominant process for the HSFL type nanograting formation with fs-laser pulses [13]. We have demonstrated that the nanostructure periodicity range increases with the material refractive index

Theoretical model

Optical properties during fs-laser excitation

Determination of HSFL grating periods

Conclusions