Formation of Homogeneous Nanostructure via Interference of Square Flattop Femtosecond Laser Pulses

We report on the formation of homogeneous nanostructures using a two-step ablation process with square flattop beams of femtosecond (fs) laser pulses. The Gaussian beam output from a ytterbium fs laser system was converted to a square flattop beam by a refractive beam shaper and a square mask. This...

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Main Authors: Takemasa Sumimoto, Godai Miyaji
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Nanomaterials
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Online Access:https://www.mdpi.com/2079-4991/15/5/355
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author Takemasa Sumimoto
Godai Miyaji
author_facet Takemasa Sumimoto
Godai Miyaji
author_sort Takemasa Sumimoto
collection DOAJ
description We report on the formation of homogeneous nanostructures using a two-step ablation process with square flattop beams of femtosecond (fs) laser pulses. The Gaussian beam output from a ytterbium fs laser system was converted to a square flattop beam by a refractive beam shaper and a square mask. This beam was split into two with a diffraction optical element, and then the downsized beams were spatially and temporally superimposed on a titanium surface. In the first step, the interference fringes of these two beams formed grooves with a period of 1.9 µm through ablation. Next, the surface was irradiated at normal incidence by a single beam to form a homogeneous line-like nanostructure with a period of 490 nm in a 53 μm square area. This nanostructure had a constant period and was formed over 95% of the laser-processed area, indicating that the ratio between the nanostructure and modification area was over six times larger than that for a Gaussian beam.
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spelling doaj-art-fd036fd0dae74f838dc915f642b401062025-08-20T02:59:15ZengMDPI AGNanomaterials2079-49912025-02-0115535510.3390/nano15050355Formation of Homogeneous Nanostructure via Interference of Square Flattop Femtosecond Laser PulsesTakemasa Sumimoto0Godai Miyaji1Faculty of Engineering, Tokyo University of Agriculture and Technology, 2-24-16, Nakacho, Koganei 184-8588, Tokyo, JapanFaculty of Engineering, Tokyo University of Agriculture and Technology, 2-24-16, Nakacho, Koganei 184-8588, Tokyo, JapanWe report on the formation of homogeneous nanostructures using a two-step ablation process with square flattop beams of femtosecond (fs) laser pulses. The Gaussian beam output from a ytterbium fs laser system was converted to a square flattop beam by a refractive beam shaper and a square mask. This beam was split into two with a diffraction optical element, and then the downsized beams were spatially and temporally superimposed on a titanium surface. In the first step, the interference fringes of these two beams formed grooves with a period of 1.9 µm through ablation. Next, the surface was irradiated at normal incidence by a single beam to form a homogeneous line-like nanostructure with a period of 490 nm in a 53 μm square area. This nanostructure had a constant period and was formed over 95% of the laser-processed area, indicating that the ratio between the nanostructure and modification area was over six times larger than that for a Gaussian beam.https://www.mdpi.com/2079-4991/15/5/355femtosecond laser processingLIPSSnanostructure formationbeam shapingflattop beam
spellingShingle Takemasa Sumimoto
Godai Miyaji
Formation of Homogeneous Nanostructure via Interference of Square Flattop Femtosecond Laser Pulses
Nanomaterials
femtosecond laser processing
LIPSS
nanostructure formation
beam shaping
flattop beam
title Formation of Homogeneous Nanostructure via Interference of Square Flattop Femtosecond Laser Pulses
title_full Formation of Homogeneous Nanostructure via Interference of Square Flattop Femtosecond Laser Pulses
title_fullStr Formation of Homogeneous Nanostructure via Interference of Square Flattop Femtosecond Laser Pulses
title_full_unstemmed Formation of Homogeneous Nanostructure via Interference of Square Flattop Femtosecond Laser Pulses
title_short Formation of Homogeneous Nanostructure via Interference of Square Flattop Femtosecond Laser Pulses
title_sort formation of homogeneous nanostructure via interference of square flattop femtosecond laser pulses
topic femtosecond laser processing
LIPSS
nanostructure formation
beam shaping
flattop beam
url https://www.mdpi.com/2079-4991/15/5/355
work_keys_str_mv AT takemasasumimoto formationofhomogeneousnanostructureviainterferenceofsquareflattopfemtosecondlaserpulses
AT godaimiyaji formationofhomogeneousnanostructureviainterferenceofsquareflattopfemtosecondlaserpulses