热物性参量对飞秒激光烧蚀金属影响的分子动力学模拟  

Influence of Thermophysical Parameters by Femtosecond Laser Ablation of Metals:Molecular Dynamics Simulation

作　　者：王新林[1] 吴鹤[1] 常彦晓[2,3] 朱卫华[1] 陈志勇[1] 陆培祥[2,3] 

机构地区：[1]南华大学电气工程学院,湖南衡阳421001 [2]华中科技大学光电子科学与工程学院 [3]华中科技大学武汉光电国家实验室,武汉430074

出　　处：《光子学报》2009年第12期3052-3056,共5页Acta Photonica Sinica

基　　金：国家重点基础研究发展计划(2006CB806006)资助

摘　　要：利用结合双温模型的分子动力学模拟方法,研究了飞秒激光与金属相互作用的烧蚀机制.采用中心波长为800nm,能量密度从0.043J.cm-2到0.40J.cm-2不等,脉宽分别为70fs和200fs的激光烧蚀金属镍和铝材料.靶材的温度、原子位型以及内部压力随时间的演化展示了材料热物性参量特性和激光参量对烧蚀结果的影响.结果显示材料电子热传导率对飞秒脉宽激光下的影响仍然较大;对比铝和镍的结果可知,铝的电子晶格耦合系数比镍的小,故电子晶格间的温度梯度持续时间较长;铝的电子热传导系数比镍的大,所以材料上下表面电子温度耦合的时间缩短.铝薄膜表面在能量密度为0.40J.cm-2激光烧蚀下呈现纳米尺寸的晶体结构.The mechanism of femtosecond（fs） laser ablating Ni and Al was investigated with molecular dynamics simulation combined with the two-temperature model. The central wavelengths and pulse duration were 800nm, 70fs and 200fs, respectively. Laser fluence ranged from 0.043Jcm-2 to 0.40Jcm-2. The evolution of temperature, atomic configuration and pressure distribution in the material revealed the influences of thermophysical parameters and laser parameters （laser fluence and pulse duration）. The result shows that the electronic thermal conductivity still has great influence on the interaction between laser and metals though using fs laser pulse. Comparing the results of fs laser ablating Ni and Al, since the electron-lattice coupling constant of Al was much smaller than that of Ni, the nonequilibrium between the electron and lattice temperature of Al continued for a longer time. The electronic thermal conductivity of Al was much larger than that of Ni, so the temperature balance time for surface and bottom electrons of Al became shorter. The surface of Al film appeared several nanometer size of crystal structure ablated with laser fluence of 0.4Jcm-2.

关 键 词：飞秒激光烧蚀 金属材料 热物性参量 双温模型 分子动力学模拟 

分 类 号：O437[机械工程—光学工程] TN249[理学—光学]