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記事一覧(39)

[FLASH,研究成果] in Opt. Mat. Express

インクを使わない着色方法 [概要] 宮崎・宮地が開発した2ステップアブレーションプロセス[特許出願済]を用いると、ステンレス鋼表面に周期サイズが均一なナノ格子を形成することができました。その表面色を評価したところ、従来の不均一な周期のナノ構造を有する表面色よりもカラーバリエーションが豊富で、かつ明るいことがわかりました。本手法を用いることにより、インクを使わない、より発色性の高いレーザーカラーマーキングへの応用が期待されます。https://www.osapublishing.org/ome/abstract.cfm?uri=ome-9-7-2902Structural coloration of a stainless steel surface with homogeneous nanograting formed by femtosecond laser ablationAbstract: Using the two-step ablation process with femtosecond (fs) laser pulses, a homogeneous nanograting with a uniform period was formed on the stainless steel. The surface color was evaluated with a photograph taken as functions of an incident angle of white light and an observation angle. We have found that the color has more variation and brightness than that of the surface with a non-uniform periodic nanostructure produced with the single-beam fs laser pulses. The results show that the nanograting can spatially disperse well the incident light into individual wavelength owing to the diffraction with high efficiency. Calculation using the grating equation reproduced the characteristic change of the colors observed as functions of these angles.

[FLASH,研究成果] in Rapid communication of JJAP

表面プラズモンの伝搬損失をレーザー光で制御可能We report a new aspect of surface plasmon polaritons excited on a nonmetallic material pumped with intense femtosecond laser pulses.[速報] 非金属表面に高強度のフェムト秒レーザーパルスを照射したときに励起される表面プラズモン・ポラリトン(SPP)について、金属表面で励起されるSPPでは見られなかった新しい現象【レーザーパルスエネルギー密度の増加によってプラズモン減衰が減少すること】について報告しました。今後、レーザーパラメータによって自在に非金属表面でのSPPの伝搬をコントロールできるようになることが期待されます。https://doi.org/10.7567/1347-4065/ab13dbReduced damping of surface plasmon polaritons on silicon with intense
femtosecond laser pulseAbstract: Using intense p-polarized 100-femtosecond laser pulses, the reflectivity of a silicon grating was measured in air as a function of the incident angle.
The angular dependent reflectivity was observed to abruptly decrease to create a sharp dip at a specific incident angle, representing the surface
plasmon resonance (SPR) induced on the grating. We have found that the sharpness of the dip increases with increasing the laser fluence. The
experimental results show that the increase in the laser fluence produces a higher density of free electrons in the surface and decreases the
plasmon damping to enhance the SPR. The calculated reflectivity reproduces well the increase in the dip sharpness with increasing the electron
density in the silicon grating surface.