Overview: With the development of industry, laser fabrication has become one of the important technologies for welding, cutting, surface processing, and other advanced manufacturing areas. At the same time, the pursuit of structures miniaturization, devices integration, and high precision has put forward more stringent requirements for laser fabrication technologies. Due to the advantages of stable mechanical and chemical properties and unique photoelectric properties, hard and brittle materials have been widely used in aerospace, the photoelectric industry, et al. Laser fabrication is an ideal technology for hard and brittle materials processing due to its high precision, high energy, and non-contact properties. In order to achieve the removal of hard and brittle materials, high laser energy is usually required, resulting in low fabrication accuracy and poor surface quality. As an improved laser processing method, liquidassisted laser fabrication can effectively improve fabrication accuracy and surface quality. The processing characteristics and material removal principles of three different liquid-assisted laser processing technologies are summarized in this review. According to the different functions of the medium through which the laser penetrates and the kinds of liquid, liquid-assisted laser fabrication technology can be divided into Laser ablation in liquid (LAL), laser-induced backside wet etching (LIBWE), and etching-assisted laser modification (EALM). The auxiliary liquid of Laser ablation in liquid is mostly water, which mainly plays the role of cooling and removing debris. The auxiliary liquids used by laser-induced backside wet etching include organic solvents, acid-base solutions, inorganic salts, and other liquids, which play different roles according to different liquids. The etching-assisted laser modification mainly uses an acid or alkaline solution as an auxiliary liquid to remove laser-modified materials. Different methods and auxiliary liquids have different mechanisms in the methods. Therefore, almost any material can be processed by choosing suitable methods and auxiliary liquids, including photosensitive glass, silicon crystal, sapphire, and other transparent hard brittle materials. Here, we summarize the fabrication technologies and fabrication parameters for different materials. The development and applications of liquid-assisted laser fabrication technologies in the fields of micro-optical components, microfluidic devices, and drilling and cutting are introduced. Finally, the challenges of the technology are discussed.

利用飞秒激光辅助刻蚀技术，在蓝宝石表面实现了周期、占空比及高度可调的光栅结构。解决了飞秒激光加工硬脆材料时表面质量较差、碎屑堆积导致的加工精度降低和难以制备深结构的问题。蓝宝石光栅结构的粗糙度从78 nm（激光直写后）降低到了7 nm（干法刻蚀后），实现了周期为800 nm光栅，以及深宽比为4的蓝宝石微结构的制备。飞秒激光辅助刻蚀技术能够制备蓝宝石表面高平滑光栅，并对光栅各级次衍射效率进行提升。

针对晶体材料几何相位元件加工难、精度低、效果差等问题，提出了利用飞秒激光诱导纳米条纹技术来实现材料内部几何相位衍射元件的制备。飞秒激光近阈值加工方式有效的提升了加工精度，其精度为340 nm。通过实时调控扫描激光的偏振可以精准控制诱导纳米条纹的方向，进而改变晶体双折射效应的慢轴方向。基于该方法实现了蓝宝石内部几何相位波带片的有效制备，器件形貌良好、无裂纹，可用于高温环境下聚焦。