激光诱导固体破坏一直是激光与物质相互作用领域的一个研究重点，蕴涵着丰富的物理意义。近十年随着超快激光在烧蚀领域的应用，其诱导的各种深亚波长结构引起广泛关注。但到目前为止，这些奇异结构的形成机制并未完全清楚。这是由于其形成涉及在超短时间尺度下局域在深亚波长空间的复杂固体电离过程：多种高度非线性电离机制，如多光子、隧穿、碰撞电离，及一些复合电离机制交织在一起，给相关研究带来很大困难；特别是，在之前研究中对上述电离机制，一般只探讨脉冲时间尺度效应的影响，而忽略结构空间尺度效应的影响。事实上，考虑超快激光诱导的典型深亚波长特征，空间尺度效应值得重点关注。在本课题中，我们将深入研究空间尺度效应对超快激光诱导固体电离的影响，探讨深亚波长尺度下由于光场及电离特性的改变，特别是纳米光学效应的出现及电离的空间尺寸限域，所导致的电离机制的改变，从而加深对超快激光诱导固体电离及深亚波长结构形成的物理本质的理解。

Since the early days of the laser science, laser-induced solid damage has been intensively studied for over four decades, not only because of its broad industrial applications, but also because of the rich physics. In the last decade, along with the application of ultrafast lasers in the field of laser ablation, the vavious deep-subwavelength structures induced by ultrafast lasers have attracted considerable interest of researchers. However, by far the mechanisms of ultrafast laser-induced deep-subwavelength structures is still unclear, which is due to the complexity of the ionization process related to the structure formation occurring at a ultra-short time scale and a deep-subwavelength spatial scale: all kinds of high nonlinear ionization mechanisms, such as multi-photon ionization, tunnelling ionization, impact ionization, and certain complex ionization mechanisms, intertwine and make the experimental and theoritical studies become very difficult; particularly, in the previous studies towards the ionization mechanisms, researchers always focus on the effects of the time scale of ultra-short laser pulses, and ignore the effects of the spatial scale of laser-induced structures. Actually, taking into account the typical deep-subwavelength characteristics induced by ultrafast laser pulses, it is clear that the effects of the spatial scale on the ionization mechanisms are worth focusing on. In the project, we will delve into the effects of the spatial scale on the ultrafast laser-induced ionization of solids, study the change of the ionization mechansisms of solids due to the change of the characteristics of light field and ionization at the deep-subwavelength scale, in particular the appearance of a variety of singular nano-optics effects and the spatial localization of the ionization process, and thus deepen our understanding about the physical nature of the ionization mechanisms of solids and the formation of deep-subwavelength structures induced by ultrafast laser.