Numerical FDTD-based simulations and Raman experiments of femtosecond LIPSS

Abstract

The article describes the results of finite-difference time-domain (FDTD) mathematical modeling of electric field strength distribution near the gold laser-induced periodic surface structures (LIPSS). Both theoretical and experimental results have been described for two fabricated morphologies: round «hill-like» and grating structures. The structures were fabricated by using a femtosecond Yb-fiber laser with a wavelength of λ=1032 nm, pulse duration τ=280 fs, and repetition rate υ=25 kHz. Morphological properties of the surfaces have been investigated by means of scanning electron microscopy (SEM). The plasmonic activity was analyzed by means of the surface-enhanced Raman spectroscopy (SERS) technique. FDTD-calculated electric field values were converted into the electromagnetic field enhancement coefficient and the theoretical SERS intensity. The prospects of the theoretical approach for LIPSS to evaluate optimal field amplification and light scattering parameters has been shown. The presented approach could be applied as a basis for performing the methods of controlled synthesis for LIPPS.

Spectral homogeneity of human platelets investigated by SERS

“…SERS substrate fabrication was performed as three-stage process based on [ 9 , 13 ]: Firstly, in order to create roughness, anodizing of titanium films with a thickness of 0.1 mm was carried out. Anodizing was performed on the laboratory hand-made equipment with a current source and a galvanic bath, in which titanium electrodes were immersed.…”

“…The modeling was carried out using the Lumerical FDTD Solutions software package (v.8.19.1584, Lumerical Inc.). Simulation algorithm was based on [ 13 ], but we have used Ti as a substrate material, instead Au. Additionally, the 11 model spheres of Au with size D = 15, 20, 25, 30 nm were added into the Ti surface ( Fig 2A ).…”

Spectral and time-resolved photoluminescence of human platelets doped with platinum nanoparticles

“…The modeling was carried out using the Lumerical FDTD Solutions software package (v.8.19.1584, Lumerical Inc.). The modeling algorithm was described in detail in [ 30 , 35 ]. However, minor modifications have been performed to adjust it for spherical NPs modeling.…”

Improving periodic uniformity of area-type LIPSS on Si wafer using a flat-top beam femtosecond NIR laser

“…Therefore, achieving uniform periodicity in LIPSS is essential for creating uniform hot spots. [27][28][29][30][31] However, hot spots induced by LIPSS fabricated at a single point are greatly affected by the line structure of a specific period, which may not be representative of the hot spots induced by LIPSS over a larger area. Therefore, it is necessary to evaluate the periodicity of LIPSS over a large area, and non-uniform hot spots can be problematic for applications requiring consistent analysis conditions and performance.…”