飞秒激光诱导微结构中飞秒时间分辨等离子体的时空动力学过程(特邀)  

Temporal-spatial Dynamics of Femtosecond Time Resolved Plasma in Femtosecond Laser Induced Microstructure(Invited)

作　　者：黄凤勤 沈天伦 司金海[1] 陈涛[1] 侯洵[1] HUANG Fengqin;SHEN Tianlun;SI Jinhai;CHEN Tao;HOU Xun(Shaanxi Key Lab of Information Photonic Technique,School of Electronic Science and Engineering,Xi'an Jiaotong University,Xi'an 710049,China)

机构地区：[1]西安交通大学电子科学与工程学院陕西省信息光子技术重点实验室,西安710049

出　　处：《光子学报》2021年第6期50-57,共8页Acta Photonica Sinica

基　　金：国家重点研发计划(No.2017YFB1104600);陕西省重点研发计划项目(No.2017ZDXM-GY-120);航空科学基金(No.20140870002)。

摘　　要：利用飞秒时间分辨泵浦探测阴影成像技术研究了不同数值孔径显微物镜聚焦的单脉冲飞秒激光诱导熔融石英微结构中等离子体的瞬态时间-空间演化特性及瞬态电子密度空间分布与激光诱导微结构的联系。实验结果表明显微物镜聚焦的飞秒激光在样品中诱导瞬态峰值电子密度随延时的增加先增大后逐渐减小。当显微物镜的数值孔径为0.45时,飞秒激光在样品中诱导瞬态峰值电子密度的空间位置随延时的增加变化不大,基本都在非线性焦点处,激光在样品中诱导的微结构是点状的;当显微物镜的数值孔径为0.3时,飞秒激光在样品中诱导瞬态峰值电子密度的空间位置随延时的增加逐渐向样品内部移动,激光诱导的微结构是长条状的。此外,不同数值孔径显微物镜聚焦飞秒激光在样品中诱导最大瞬态电子密度的空间位置与激光诱导微结构的位置一致,这说明飞秒时间分辨泵浦探测阴影成像可用于超快激光微加工过程的在线检测,可为超快激光诱导材料微结构的定向调控及加工参数优化提供参考。Temporal-spatial evolutions of transient plasma in single pulse femtosecond(fs)laser induced microstructure in fused silica were investigated using fs time-resolved pump-probe shadowgraphy.The relation between the spatial distribution of transient electron density and the distribution of fs laser-induced microstructure in fused silica were also studied.In this study,the fs laser was focused by two kinds of microscope objectives with different Numerical Aperture(NA).The results showed that the transient peak electron density indued by focused fs laser was increased and then decreased as delay time of probe beam increased.When the NA of the microscope objective was 0.45,the spatial position of transient peak electron density induced by fs laser did not moved as delay time increased,which basically kept at the nonlinear focus.The fs laser-induced microstructure in the sample was punctate.When the NA of the microscope objective was 0.3,the spatial position of transient peak electron density induced by fs laser moved from the sample surface to the inside of the sample as delay time increased.The fs laser-induced microstructure in the sample was long strips.In addition,we found that the spatial position of fs laserinduced maximum transient electron density was consistent with the position of laser-induced microstructure when fs laser was focused by the two different microscope objective.Those results imply that fs time-resolved pump-probe shadowgraphy may be used for online monitoring fs laser processing process,which can provide references for directional control of ultrafast laser-induced material microstructure and optimization of machining parameters.

关 键 词：飞秒激光 泵浦探测阴影成像 等离子体 微纳加工 数值孔径 

分 类 号：TN249[电子电信—物理电子学]