国立大学法人東京農工大学 大学院工学研究院先端物理工学部門の宮地 悟代 教授、同大学大学院工学府化学物理工学専攻の住本 武優 氏らの研究チームは、チタン表面に高強度のフェムト秒レーザーパルス[注2]を照射するだけで、周期が490 ナノメートル（nm；ナノメートルは1ミリメートルの百万分の一）で一定で直線性の良いナノ構造体を、固体表面から直接削り出だせる技術を開発しました。この技術により、固体表面に撥水性や親水性のような力学的制御機能だけでなく、光の反射や吸収などこれまでにない光学的制御機能を容易に与えることができると期待されます。
掲載論文情報
掲載誌：nanomaterials
出版日：2025年2月25日付（電子版）
論文名：Formation of homogeneous nanostructure via interference of square flattop femtosecond laser pulses
著者名：Takemasa Sumimoto & Godai Miyaji*
https://www.mdpi.com/2079-4991/15/5/355
DOI ：10.3390/nano15050355
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.