Nanotubular Arrayed LIPSS Achieved with Femtosecond Bessel Beam on Silver Surface for SERS-Based Multiple Explosive Sensing

Arising from ultrashort laser–matter interactions, laser-induced periodic surface structures (LIPSS) have evolved into promising applications in various fields, such as nanophotonics, solar energy conversion, photodetectors, photocatalysis, and sensing. This study presents the creation of a novel nanotubular arrayed silver (Ag) LIPSS utilizing an axicon-generated femtosecond Bessel beam. A meticulous exploration has unraveled the mechanism behind Bessel beam-induced LIPSS formation, revealing how the modulation of the ablation fluence profile, intertwined with the interaction of photon-induced surface plasmon polariton (SPP) and the incident beam, plays a pivotal role. The influence of the Bessel beam profile and the SPP decay length have been crucial factors in crafting such distinctive nanostructures. The period (Λ) of the fabricated low spatial frequency LIPSS stands estimated at 575 ± 10 nm. The distinct topographical characteristics of Ag nanostructures generated using a Gaussian beam with identical fluence are also presented. Furthermore, these plasmonic nanostructures have exhibited exceptional efficacy and versatility as active substrates for surface-enhanced Raman scattering (SERS)-based sensing applications. Traces of real-time explosives such as TNT, tetryl, RDX, and HMX with the lowest concentrations ranging from 50 to 500 nM have been successfully detected. The achieved enhancement factors hovered around 10 6, rendering these substrates highly practical for real-world applications. Moreover, our investigation of the BB ablation process unveiled its promising applications in creating antireflection surfaces. En bloc, this study significantly enhances the knowledge on the unexplored research area of Bessel beam–metal interaction, leading to the formation of exotic nanotubular LIPSS, demonstrating versatile SERS-based sensing applications.