Ultrafast laser filamentation results from the interaction of ultrafast laser with Kerr media. During filamentary propagation, the transparent medium is altered by numerous linear and nonlinear effects of ultrashort laser pulses. Filamentation can cause material modification in solids through laser energy deposition and ionization processes, which creates a new opportunity for ultrafast laser processing of materials when combined with filamentary propagation characteristics, such as intensity champing and long propagation distance. This paper reviews the research on ultrafast laser filamentation in solids for micro- and nano-processing, including the fundamental physics, filamentation characteristics, and applications in solids for ultrafast laser filamentation-induced processing. Additionally highlighted are the difficulties and potential applications for solid-based filamentation-induced processing.

从解决陶瓷齿轮加工困难的实际应用需求出发,系统研究1064 nm皮秒激光的输出功率、扫描速度、扫描次数、扫描线间距等工艺参数对陶瓷切削深度、宽度和表面粗糙度的影响;结合齿轮结构的几何特征,采用将柱状工件的曲面加工转换成平面加工的方法,完成了不同齿形(直齿、斜齿)陶瓷齿轮的激光直接高精制造,齿面平均粗糙度Ra≤2 μm,加工效率高,可适用于不同材质齿轮类复杂构型零件的加工。

Currently, laser-induced structural modifications in optical materials have been an active field of research. In this paper, we reported structural modifications in the bulk of sapphire due to picosecond (ps) laser filamentation and analyzed the ionization dynamics of the filamentation. Numerical simulations uncovered that the high-intensity ps laser pulses generate plasma through multi-photon and avalanche ionizations that leads to the creation of two distinct types of structural changes in the material. The experimental bulk modifications consist of a void like structures surrounded by cracks which are followed by a submicrometer filamentary track. By increasing laser energy, the length of the damage and filamentary track appeared to increase. In addition, the transverse diameter of the damage zone increased due to the electron plasma produced by avalanche ionizations, but no increase in the filamentary zone diameter was observed with increasing laser energy.

采用紫外皮秒激光在As₂Se₃玻璃表面以线扫描形式快速制备大面积周期性点阵式增透微结构，获得了红外透光性能提高的硫系玻璃样品。研究确定了As₂Se₃玻璃的激光刻蚀阈值，并研究设计了合适线扫描工艺方法。所制样品相对于原样在波长11.0 μm~12.4 μm范围内，透过率平均提高10.0 %；波长13.0 μm~14.2 μm范围内，透过率平均提高5.2 %。激光扫描制备方法没有破坏样品表面原有的浸润性，整个制备过程均在空气开放环境下进行，成本低，工艺可控性强，效率高，制备8 mm×8 mm的表面微结构，仅用时3.65 s，且表面微结构单元尺寸及间距可按材料应用需求调控。分析表明，当激光能量较低时，对该硫系玻璃的去除以“冷加工”为主，不会有明显的热效应，得到微结构的硫系玻璃表面元素组成未发生改变；激光能量较高时，会存在一定的热效应，使得刻蚀点出现熔融态，在微坑边缘出现凸起或翻边。

以波长为1064 nm的超短脉冲激光(脉宽为10 ps)作为成丝激发源, 引导自聚焦效应在蓝宝石内部产生了突破瑞利长度限制的成丝线迹。利用成丝区因相变而造成的与材料其他区域物相的不同, 辅以化学腐蚀的方法, 获得了切面粗糙度为800 nm的蓝宝石切割件, 该技术可实现自由路径切割。分析了皮秒激光的成丝特征和技术实现的工艺参数, 确定了皮秒激光在蓝宝石内的自聚焦阈值功率为2.78×106 W, 探究了激光峰值功率、聚焦位置及辐照点脉冲数对皮秒激光在蓝宝石内部成丝起始位置和切割质量的影响, 获得了实现蓝宝石高精度切割的工艺参数。

分别采用波长为532 nm的短脉冲激光(脉宽6 ns)和超短脉冲激光(脉宽15～20 ps)对蓝宝石进行基本作用规律的研究, 探究了多/单脉冲烧蚀点直径与功率的关系, 分析脉冲数与材料阈值的关系, 确定材料阈值。并且对相关作用机理进行系统的对比分析。研究结果表明, 烧蚀点直径的平方与脉冲峰值功率的对数呈线性关系, 根据关系式计算得出光斑半径与实际测量值相符, 并且材料阈值随脉冲数的增加而降低。纳秒绿激光烧蚀蓝宝石材料主要是基于光热作用的机理, 而皮秒激光烧蚀蓝宝石材料在以“电子态”冷去除的同时, 还兼具一些非线性效应。