Sub-micron and nanosized features in laser-induced periodic surface structures

The present report concentrates on little known peculiarities of laser-induced periodic surface structures (LIPSS) on metals and alloys formed upon irradiation by linearly polarized Ti/sapphire femtosecond laser pulses with the energy density of 0.17–1.0 J/cm 2 in air environment. The peculiarities...

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Bibliographic Details
Published in:Indian journal of physics 2019-04, Vol.93 (4), p.495-502
Main Authors: Berezovska, N., Dmitruk, I., Vovdenko, S., Yeshchenko, O., Teselko, P., Dmytruk, A., Blonskyi, I.
Format: Article
Language:English
Subjects:
Aerodynamics
Astrophysics and Astroparticles
Dislocations
Femtosecond pulses
Flux density
Lasers
Linear polarization
Noble metals
Original Paper
Physics
Physics and Astronomy
Plane waves
Positive feedback
Reduction
Sapphire
Second harmonic generation
Substrates
Surface roughness
Titanium
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Summary:The present report concentrates on little known peculiarities of laser-induced periodic surface structures (LIPSS) on metals and alloys formed upon irradiation by linearly polarized Ti/sapphire femtosecond laser pulses with the energy density of 0.17–1.0 J/cm 2 in air environment. The peculiarities discussed are spontaneous twofold reduction in period and appearance of dislocations in the quasi-grating LIPSS. The twofold reduction in period is interpreted as a result of the second harmonic generation (SHG) of the laser light on the surface, stimulated and enhanced by surface roughness. LIPSS with two times shorter period stimulate SHG, and in this way a positive feedback mechanism works. The dislocations in the LIPSS are explained as the interference of scattered wave, which may contain optical vortices, with the incident plane wave. The quasi-grating with the dislocations works as a spatial phase modulator for the scattered wave and provides a positive feedback for enhancement of the dislocations. A successful example of application of LIPSS on noble metals as a SERS substrate and a discussion of their features important for such application is presented.
ISSN:0973-1458
0974-9845
DOI:10.1007/s12648-018-1323-0