利用超快小角X射线散射探测二氧化硅薄膜上飞秒激光诱导周期表面结构的形成
Probing the formation of femtosecond laser-induced periodic surface structures on silica films by ultrafast small-angle X-ray scattering
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中文总结 AI 辅助
本研究利用超快小角X射线散射实时探测飞秒激光在二氧化硅薄膜上诱导周期表面结构的形成，提出包含纳米散射体与裂纹演化及脉冲间反馈的五阶段模型。
中文摘要 AI 辅助
由X射线自由电子激光器（XFELs）提供的超短X射线脉冲，为探测尺寸甚至低于光学衍射极限的激光诱导纳米结构提供了独特的机会，其空间和时间分辨率分别达到亚微米和亚皮秒量级。利用超快小角X射线散射（SAXS），我们在倒易空间中探测纳米散射体和纳米裂纹的形成，观察它们在二氧化硅薄膜上演变为不同类型的激光诱导周期表面结构（LIPSS）的过程。我们重点关注纳米散射体和空间周期低于100纳米的高空间频率LIPSS（HSFL）的动力学与演化。我们的实验包括在固定样品位置对HSFL的逐脉冲演化进行原位分析，以及利用超快泵浦-探测方案进行的飞秒时间分辨延迟和通量扫描。我们发现，纳米散射体和周期性纳米裂纹在数百皮秒的延迟时间形成，随后演化为HSFL。在低激光通量下，多脉冲辐照期间脉冲间孵育效应变得重要。同时，脉冲间反馈导致HSFL的有序化并提高其规则性。实验辅以理论分析，包括数值时域有限差分（FDTD）模拟。这些综合分析使我们能够提出一个五阶段模型，描述飞秒激光脉冲辐照下二氧化硅薄膜上LIPSS的形成过程。
英文摘要
Ultrashort X-ray pulses, as provided by X-ray Free Electron Lasers (XFELs), offer unique opportunities to probe the formation of laser-induced nanostructures with sizes even below the optical diffraction limit, with sub-micometer and sub-picosecond spatial and temporal resolution. Using ultrafast small-angle X-ray scattering (SAXS), we probe the formation of nanoscatterers and nanocracks in reciprocal space as they evolve into different types of laser-induced periodic surface structures (LIPSS) on silica films. Our focus is on the dynamics and evolution of nanoscatterers and high spatial frequency LIPSS (HSFL), with spatial periods below 100 nm. Our experiments include an in-situ analysis of the pulse-by-pulse evolution of HSFL at a fixed sample location, as well as fs time-resolved delay and fluence scans using an ultrafast pump-probe scheme. We find that nanoscatterers and periodic nanocracks form at delay times of hundreds of picoseconds and subsequently evolve into HSFL. At low laser fluences, inter-pulse incubation effects become important during multi-pulse irradiation. Simultaneously, inter-pulse feedback leads to an ordering and improve the regularity of the HSFL. The experiments are complemented by theoretical analyses, including numerical Finite-Difference Time-Domain (FDTD) simulations. These combined analyses allow us to propose a five-stage model of LIPSS formation on silica films upon irradiation with fs-laser pulses.
发表机构
- University of Duisburg-Essen（杜伊斯堡-埃森大学）
- Bentley Systems, Incorporated（宾利系统公司）
- European XFEL（欧洲自由电子激光实验室）
- Bundesanstalt für Materialforschung und -prüfung (BAM)（联邦材料研究与测试研究所）
- Warsaw University of Technology（华沙理工大学）
- Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所）
- SLAC National Accelerator Laboratory（斯坦福直线加速器中心）
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