Formation of periodic surface structures on dielectrics after irradiation with laser beams of spatially variant polarisation: a comparative study

Abstract

A comparative study is performed to explore the periodic structure formation upon intense femtosecond pulsed irradiation of dielectrics with radially and azimuthally polarised beams. Laser conditions have been selected appropriately to produce excited carriers with densities below the optical breakdown threshold in order to highlight the role of phase transitions in surface modification mechanisms. The frequency of the laser induced structures is calculated based on a theoretical model that comprises estimation of electron density excitation, heat transfer, relaxation processes, and hydrodynamics-related mass transport. The influence of the laser wavelength in the periodicity of the structures is also unveiled. The decreased energy absorption for azimuthally polarised beams yields periodic structures with smaller frequencies which are more pronounced as the number of laser pulses applied to the irradiation spot increases. Similar results are obtained for laser pulses of larger photon energy and higher fluences. All induced periodic structures are oriented parallel to the laser beam polarisation.

Laser engineering of biomimetic surfaces

“…In 2011, Hnatovsky et al used complex polarization states including the presence of the longitudinal component of the electric field for sub-wavelength resolution diagnostic tool [251], which was lately used as a simple method to characterize intense Laguerre-Gauss vector vortex beams [252]. Due to the ability of the CV beams to produce complex morphologies the use of complex polarization states and cylindrically polarized laser pulses have widely been used to increase the directional complexity of LIPSS for various materials including metals [167,229,253,254] semiconductors [238,[255][256][257] and dielectric surfaces [230]. Fig.…”

Generation of Supra-Wavelength Grooves in Femtosecond Laser Surface Structuring of Silicon

“…Grooves formation has been first reported in semiconductors (Si, InP, etc.) [ 21 , 22 , 23 , 24 ] and successively observed also in dielectrics (e.g., SiO 2 ) [ 25 , 26 ] and in various metals and alloys (e.g., Ni, Ti, steel, etc.) [ 27 , 28 , 29 ].…”

“…has yet to be fully clarified. For example, differently from ripples, the periodicity of the grooves increases as a function of both laser fluence and pulse number [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. These observations, in turn, suggest that the mechanisms leading to supra-wavelength grooves generation might involve processes different from those leading to ripples formation that still deserve careful investigations.…”

Flexible 3D Printed Conductive Metamaterial Units for Electromagnetic Applications in Microwaves

“…To date, several 3D printing methods have been developed, namely, stereo-lithography, selective laser sintering, digital light processing, binder printing, inkjet printing and laminate object manufacturing [ 23 , 24 ]. Among them stands the Fused Deposition Modeling (FDM) or Fused Filament Fabrication (FFF) method, which is an effective 3D printing technique that uses long wires of thermoplastic materials called filaments.…”