Laser printed nano-gratings: orientation and period peculiarities

Abstract

Understanding of material behaviour at nanoscale under intense laser excitation is becoming critical for future application of nanotechnologies. Nanograting formation by linearly polarised ultra-short laser pulses has been studied systematically in fused silica for various pulse energies at 3D laser printing/writing conditions, typically used for the industrial fabrication of optical elements. The period of the nanogratings revealed a dependence on the orientation of the scanning direction. A tilt of the nanograting wave vector at a fixed laser polarisation was also observed. The mechanism responsible for this peculiar dependency of several features of the nanogratings on the writing direction is qualitatively explained by considering the heat transport flux in the presence of a linearly polarised electric field, rather than by temporal and spatial chirp of the laser beam. The confirmed vectorial nature of the light-matter interaction opens new control of material processing with nanoscale precision.

Manipulation of LIPSS orientation on silicon surfaces using orthogonally polarized femtosecond laser double-pulse trains

“…The perio Fourier transf the period of scanning dire "V+H" repres the correspon the term "H+ the LIPSS pe average perio range and me study exhibite patterning [33 ations of , with an he period ed in this e surface situation where the vertically polarized pulse served as the leading pulse while "H+V" represents a situation where the horizontally polarized pulse served as the leading pulse…”

Femtosecond laser-induced melting and shaping of indium nanostructures on silicon wafers

“…As it is shown in Ref. 21, the nano-grating period and its tilt angle depends on the angle between the laser polarization direction and raster scan direction. In our work, the angle between the laser polarization direction and raster scan direction is zero.…”

Fabrication of Periodic Nanostructures on Silicon Suboxide Films with Plasmonic Near-Field Ablation Induced by Low-Fluence Femtosecond Laser Pulses

“…For the excitation of SPPs, that is, for evanescent waves to exist in the vicinity of the surface, the relation Re[ε a ] < 0 should be satisfied [42]. The excitation of the SPPs is the origin of the periodicity of the fs laser-induced nanostructure formation, and periodic nanoablation is induced by a fine spatial distribution of electromagnetic energy in the surface layer [32,33,[43][44][45][46][47][48][49][50][51]. To form the stationary energy distribution, the following two processes were proposed: the interference between the incident laser beam and the SPPs [43][44][45], and the counter-propagating SPP interference, i.e., the generation of a standing wave mode of SPPs [32,33,[46][47][48][49][50][51].…”

“…At τ < 0.5 fs, D was calculated to approach 200 nm. If the SPPs are resonantly excited, where ε a + ε b becomes zero [42,50], D could be 267 nm for τ = 1 fs at N e = 1.0 × 10 22 cm −3 . Here, N e for these values of D is much larger than the critical plasma density of 1.7 × 10 21 cm −3 .…”