Author Affiliations
Abstract
Ultrafast Laser Laboratory, School of Precision Instruments and Optoelectronics Engineering, Key Laboratory of Optoelectronic Information Technology (Ministry of Education), Tianjin University, Tianjin 300072, China
Investigations are performed to explore high-repetition-rate femtosecond laser ablation effects on the physical and chemical properties of poly(methyl methacrylate) (PMMA). A scanning electron microscopy (SEM) is used to characterize the morphology change in the laser-ablated regions. The infrared and Raman spectroscopy reveals that the fundamental structure of the PMMA is altered after laser ablation. We demonstrate the cumulative heating is much greater during high-repetition-rate femtosecond laser ablation, supporting a photothermal depolymerization mechanism during the ablation process.
140.7090 Ultrafast lasers 140.3390 Laser materials processing Chinese Optics Letters
2015, 13(7): 070003
天津大学光电信息技术科学教育部重点实验室, 天津 300072
利用50 MHz和1 MHz的重复频率光子晶体光纤飞秒激光分别在45#钢表面产生了微浮雕结构。实验发现微浮雕结构的高度和宽度与入射激光功率、激光扫描速度以及脉冲重复频率有关。通过调整这些参数, 可以实现对微浮雕形态结构的精确控制。对微浮雕结构的产生机制进行了初步分析, 发现微浮雕结构的产生与高重复频率飞秒激光的热积累效应有关。热积累导致了45#钢的表面熔化, 在液体表面张力和温度梯度力共同作用下, 产生了微浮雕结构。
激光技术 飞秒激光微纳加工 微浮雕结构 光子晶体光纤飞秒激光器 高重复频率
Author Affiliations
Abstract
Ultrafast Laser Laboratory, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Key Laboratory of Opto-Electronic Information Technical Science, Ministry of Education of China, Tianjin 300072, China
We observe the morphological change and grain structure of Ni foil when it is ablated with femtosecond laser pulses. Scanning electron microscopy and ˉeld emission transmission electron microscopy are used to study the nature of the morphology and grain structure of nickel foil and determine the essential features. The results indicate that there are many random nanostructures in the center of the ablated region composed of nanocrystalline grains as well as some core-shell structures. The observed morphologies seem to suggest that phase explosion and extremely high cooling rate are the most probable physical mechanisms responsible for the formation of surface nanostructures.
激光烧蚀 飞秒激光 金属 表面形貌 140.7090 Ultrafast lasers 140.3390 Laser materials processing 320.7130 Ultrafast processes in condensed matter, including semiconductors 160.3900 Metals Chinese Optics Letters
2010, 8(1): 38
1 中国工程物理研究院激光聚变研究中心,四川 绵阳 621900
2 天津大学 精密仪器与光电子工程学院超快激光实验室；光电信息技术科学教育部重点实验室，天津300072
利用聚焦的飞秒激光（中心波长775 nm、脉宽150 fs）照射FOTURAN光敏玻璃，经热处理及浓度为8％的氢氟酸溶液室温腐蚀50 min后，在FOTURAN玻璃表面制作了微凹面.利用原子力显微镜和扫描电子显微镜分析了微凹面的形貌，发现它具有光滑璧面和清晰边缘，直径约为几十微米.通过分别改变入射激光的单脉冲能量(970~3250 nJ)和脉冲数目(10~3000个)，研究了它们对微凹面制作结果的影响，发现了微凹面的直径随激光入射参量的饱和效应，并解释了其原因；指出了飞秒激光在FOTURAN上制作微结构的应用.
飞秒激光 微凹面 微细加工 FOTURAN玻璃 光敏玻璃 Femtosecond laser Micro-concave-surface Micromachining FOTURAN glass Photosensitive glass
天津大学精密仪器与光电子工程学院超快激光研究室 光电信息技术科学教育部重点实验室, 天津 300072
以掺镱大模面积光子晶体光纤(PCF)飞秒激光放大器为光源组建了一套结构紧凑且运行稳定的飞秒激光微纳加工系统,中心波长为1040 nm, 重复频率50 MHz, 最大平均功率16 W, 光栅压缩后脉冲宽度85 fs。利用该套系统在硅片、金属薄膜(Cr膜、Al膜)上演示了微图案的刻划, 并与采用重复频率1 kHz的固体钛宝石飞秒激光放大器的加工结果进行对比, 发现利用新组建的加工系统进行微纳加工, 由于单脉冲能量较小且便于调节, 使得刻划微图案时边缘加工效果更容易控制, 且避免了加工过程中未加工区域受到的污染, 保护了制作衬底。显示了该套系统高重复频率和高平均功率的特性及其在改善微纳加工效果及明显提高加工效率方面的优势。
激光技术 飞秒激光微纳加工 微图案刻划 光子晶体光纤飞秒激光放大器 高重复频率 高平均功率
天津大学 精密仪器与光电子工程学院 超快激光研究室，天津 300072
为了定量分析飞秒激光金属加工中的热影响，基于一个二维的双温模型，采用有限差分法计算了飞秒激光烧蚀金属镍的径向热影响区。提出一种飞秒激光烧蚀热影响区定义，把热影响区定义为两部分，一部分是熔化再凝固区(晶格温度介于相爆炸温度和熔化温度之间的区域)，另一部分是热激活区(晶格温度介于熔化温度和热激活温度之间的区域)。通过研究表层晶格不同时刻的径向温度分布，得到飞秒激光烧蚀500nm厚金属镍的径向热影响区是160nm。结果表明，飞秒激光加工的热影响区非常小，可以实现对金属材料的超精密加工。并分析了电子热导率和电子比热容对径向热影响区的影响。
超快光学 热影响区 有限差分 双温模型 ultrafast optics heat affected zone finite-difference two temperature model
Author Affiliations
Abstract
1 School of Science, Civil Aviation University of China, Tianjin 300300
2 Ultrafast Laser Laboratory, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072
3 Key Laboratory of Optoelectronic Information Technical Science, Ministry of Education of China, Tianjin 300072
Micro-deposition of an aluminum film of 500-nm thickness on a quartz substrate was demonstrated by laser-induced forward transfer (LIFT) using a femtosecond laser pulse. With the help of atomic force microscopy (AFM) and scanning electron microscopy (SEM), the dependence of the morphology of deposited aluminum film on the irradiated laser pulse energy was investigated. As the laser fluence was slightly above the threshold fluence, the higher pressure of plasma for the thicker film made the free surface of solid phase burst out, which resulted in that not only the solid material was sputtered but also the deposited film in the liquid state was made irregularly.
飞秒激光 激光诱导向前转移技术 薄膜 微沉积 140.7090 Ultrafast lasers 220.4000 Microstructure fabrication 160.3900 Metals Chinese Optics Letters
2007, 5(5): 308
天津大学精密仪器与光电子工程学院超快激光研究室,光电信息技术科学教育部重点实验室,天津,300072
本文介绍了飞秒激光的特性以及超短脉冲激光与材料相互作用的机理,并着重指出了其与长脉冲激光的区别.飞秒激光可产生超高光强、具有精确的损伤阈值(并且损伤阈值较低较低)、很小的热影响区、几乎可精密加工所有种类材料,并且,加工精度极高,可进行亚微米尺寸的精密加工.通过分析飞秒激光材料微加工的特性,综述超短脉冲激光材料微加工的应用研究现状.
激光技术 飞秒激光 激光微加工 微结构改性 多光子吸收 光子晶体 laser lechniques femtosecond laser laser micromachining multiphoton absorption phonic crystal
