多维整形超快激光诱导高空间频率周期表面纳米结构的超快动力学

20年来，大量文献报导了飞秒激光诱导高空间频率表面周期结构（HSFL）。亟待解决的问题主要是两方面： HSFL的形成机制；高效率制备一致、规则的HSFL。.目前主要采用扫描电镜等方法，研究凝固表面的HSFL。本项目创新发展泵浦-探测方法，利用红外光飞秒激光作为泵浦光，紫外光激光作为探测照明光。发展激光空间、时频域多维整形，调控在探测光相平面上泵浦光的焦斑面积与空间分布，建立高空间分辨（<200nm）高时间分辨的超快成像系统，研究HSFL的超快过程。开展飞秒激光诱导HSFL的理论研究，揭示HSFL的形成机制。.多脉冲累积照射会出现周期纳米结构的扭曲、分叉、断裂等。本项目综合超快成像、时频域与空间整形等，调控表面波（表面波代表有待深入研究的HSFL的起源）的相干共振增强与热效应的抑制，发展高效率制备一致、规则HSFL的新原理、新方法，研究在偏振微光学元器件、超表面、表面特性调控等领域的应用。

In the last two decades, a large amount of researches focuse on femtosecond laser-induced periodic surface structures (LIPSS), especially high spatial frequency LIPSS (HSFL). There are two key problems to be solved: one is the formation mechanism of HSFL, and the other is how to fabricate regular and uniform HSFL..SEM and AFM are widely used to study the HSFL of the solidified surface after laser ablation. In this project, 1030 nm femtosecond laser is used as the pump laser, and the 343 nm laser is the illumination light. We study spatiotemporal shaping of pump laser to adjust the focal spot area and intensity distribution at the phase plane of the probe light. Establish the ultrafast imaging set-up with a high spatial resolution (<200nm) and high temporal resolution, and study the ultrafast process of the formation of HSFL. Develop a theoretical model to study the interaction between femtosecond laser and sample surface, and reveal the formation mechanism of HSFL..The fabrication of uniform and regular periodic surface nanostructures requires the enhanced periodic energy deposition and the reduced residual heat of laser ablation. By integrating ultrafast imaging and spatiotemporal shaping, coherently enhance the surface waves and periodic deposition of laser energy, and depress thermal effects of laser ablation. Efficiently fabricate HSFL with high uniformity and regularity. In the last, we will explore the applications of HSFL in the fields of birefringence optical elements, metasurfaces, and surface property manipulation.