飞秒脉冲激光烧蚀金属的机理分析
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摘要
为了深入理解超短脉冲激光烧蚀金属的机理,特别是烧蚀过程中靶面电子发射带来的影响,本文分析了飞秒脉冲激光烧蚀金属的机理,并在此基础上建立了一维热传导双温模型,模型考虑了电子热导率、热容、电子-晶格耦合系数等参数随温度的变化,以及表面热电子发射和多光子电离导致靶面的能量损失。选择波长为800 nm,FWHM为100 fs,峰值功率密度为1.2×10~(17) W/m~2的高斯型单脉冲激光辐照铜靶进行数值模拟。并对计算数据进行分析,结果表明:多光子电离所导致的电子发射比热电子发射要强,但是热电子发射持续的时间长;多光子电离导致的电子发射带走的靶面能量比较大,在分析飞秒烧蚀过程中不可忽略。
In order to understand the mechanism of metal ablation by ultrashort pulsed laser,especially the effect of electron emission from the target surface during ablation,the mechanism of the interaction between femtosecond pulse laser and metal material is theoretically analyzed in this paper,and based on this,an one-dimensional two-temperature model is established.In the model,many parameters changing with temperature are taken into account,such as thermal conductivity,heat capacity,electron-lattice coupling coefficient et al,as well as the energy loss caused by thermal electron emission and multiphoton ionization emission at the boundary.The ablation process of the copper target irradiated by a Gauss type single pulse laser with a peak power density of 1.2×10~(17) W/m~2,a wavelength of 800 nm and FWHM of 100 fs is numerically simulated.The results show that the electron emission caused by multiphoton ionization is stronger than that of heat electron emission,but the duration of the thermal electron emission is longer;The energy loss of the electron emission caused by the multiphoton ionization is very high,which should not be ignored during the analysis of the femtosecond ablation process.
In order to understand the mechanism of metal ablation by ultrashort pulsed laser,especially the effect of electron emission from the target surface during ablation,the mechanism of the interaction between femtosecond pulse laser and metal material is theoretically analyzed in this paper,and based on this,an one-dimensional two-temperature model is established.In the model,many parameters changing with temperature are taken into account,such as thermal conductivity,heat capacity,electron-lattice coupling coefficient et al,as well as the energy loss caused by thermal electron emission and multiphoton ionization emission at the boundary.The ablation process of the copper target irradiated by a Gauss type single pulse laser with a peak power density of 1.2×10~(17) W/m~2,a wavelength of 800 nm and FWHM of 100 fs is numerically simulated.The results show that the electron emission caused by multiphoton ionization is stronger than that of heat electron emission,but the duration of the thermal electron emission is longer;The energy loss of the electron emission caused by the multiphoton ionization is very high,which should not be ignored during the analysis of the femtosecond ablation process.
引文
[1] Chichkov BN,Momma C,Nolte S,et al.Femtosecond,picosecond and nanosecond laser ablation of solids[J].Applied physics A,1996,63(2):109-115.
[2] Anisimov S I,Kapeliovich B L,Pemlman T L.Electron emission from metal surfaces exposed to ultrashort laser pulses[J].Soviet Physics-JETP,1974,39:375.
[3] Yunpeng Ren,J K Chen,Yuwen Zhang.Optical properties and thermal response of copper films induced by ultrashort-pulsed lasers[J].Journal of Applied physics,2011,110,113102.
[4] TAN Xinyu,WEI Huili,MAO Feng,et al.Effect of electronic thermal conductivity on properities of gold target material of femtosecond laser ablation[J].Chinese Journal of rare metals,2011,35(5):704-708.(in Chinese)谭新玉,魏慧丽,毛峰,等,高能飞秒激光烧蚀金靶材的动态热导率影响的研究[J].稀有金属,2011,35(5):704-708.
[5] Guangqing Du,Qing Yang,Feng Chen et al.Ultrafast dynamics of thermionic emission on Au film under femtosecond laser exitation[J].Appl phys,A,2013,112:479-483.
[6] LI Zhiming,NIE Jinsong,HU Yuze,et al.Heat accumulation effects on the ablation of silocon with high frequency Femtosecond laser[J].Laser & Infrared,2017,47(4):410-415.(in Chinese)李志明,聂劲松,胡瑜泽,等,高频飞秒激光对硅材料烧蚀的热累积效应[J].激光与红外,2017,47(4):410-415.
[7] DING Wenyu,WANG Bangfu,WANG Zhongwang,et al.Study on thermal relaxation in the process of copper sheet ablation by high frequency femtosecond laser[J].Laser & Infrared,2018,48(5):544-549.(in Chinese)丁雯钰,汪帮富,王中旺,等.高频飞秒激光对铜片烧蚀过程热弛豫现象研究[J].激光与红外,2018,48(5):544-549.
[8] Ling Zhou,Ling Li.Melting and resolidification of gold film irradiated by laser pulses less than 100fs[J].Applied Physics A,2014,116:2157-2165.
[9] G Al-Malkawi,A Hassanein.Non-equilibrium two-dimensional thermal evolutions in target materials irradiated by femtosecond laser pulse[J].Laser and Particle Beams,2014,(32):33-39.
[10] CHEN Anmin,GAO Xun,JIANG Yuanfei,et al.Numerical simulation of femtosecond laser heating of metal films using electron thermal emission[J].ACTA PHYSICA SINICA,2010,59(10):7198-7201.(in Chinese)陈安民,高勋,姜远飞,等,数值模拟飞秒激光加热金属的热电子发射[J].物理学报,2010,59(10):7198-7201.
[11] XU Bin,WU Xiaoyu,LING Shiquan,et al.Numerical simulation of thermal electron emission in metal films ablated by multi-pulse femtosecond laser[J].Laser & Optoelectronics Progress,2012,49:083201.(in Chinese)徐斌,伍晓宇,凌世全,等,多脉冲飞秒激光烧蚀金属箔的热电子发射数值分析[J].激光与光电子学进展,2012,49:083201.
[12] Sha Tao,Benxin Wu.The effect of emitted electrons during femtosecond laser-metal interactions:A physical explanation for coulomb explosion in metals[J].Appied Surface Science,2014,298:90-94.
[13] Zhaoyang Chen,Samuel S Mao.Femtosecond laser-induced electronic plasmas at metal surface[J].Applied Physics Letters,2008,93:051506.
[2] Anisimov S I,Kapeliovich B L,Pemlman T L.Electron emission from metal surfaces exposed to ultrashort laser pulses[J].Soviet Physics-JETP,1974,39:375.
[3] Yunpeng Ren,J K Chen,Yuwen Zhang.Optical properties and thermal response of copper films induced by ultrashort-pulsed lasers[J].Journal of Applied physics,2011,110,113102.
[4] TAN Xinyu,WEI Huili,MAO Feng,et al.Effect of electronic thermal conductivity on properities of gold target material of femtosecond laser ablation[J].Chinese Journal of rare metals,2011,35(5):704-708.(in Chinese)谭新玉,魏慧丽,毛峰,等,高能飞秒激光烧蚀金靶材的动态热导率影响的研究[J].稀有金属,2011,35(5):704-708.
[5] Guangqing Du,Qing Yang,Feng Chen et al.Ultrafast dynamics of thermionic emission on Au film under femtosecond laser exitation[J].Appl phys,A,2013,112:479-483.
[6] LI Zhiming,NIE Jinsong,HU Yuze,et al.Heat accumulation effects on the ablation of silocon with high frequency Femtosecond laser[J].Laser & Infrared,2017,47(4):410-415.(in Chinese)李志明,聂劲松,胡瑜泽,等,高频飞秒激光对硅材料烧蚀的热累积效应[J].激光与红外,2017,47(4):410-415.
[7] DING Wenyu,WANG Bangfu,WANG Zhongwang,et al.Study on thermal relaxation in the process of copper sheet ablation by high frequency femtosecond laser[J].Laser & Infrared,2018,48(5):544-549.(in Chinese)丁雯钰,汪帮富,王中旺,等.高频飞秒激光对铜片烧蚀过程热弛豫现象研究[J].激光与红外,2018,48(5):544-549.
[8] Ling Zhou,Ling Li.Melting and resolidification of gold film irradiated by laser pulses less than 100fs[J].Applied Physics A,2014,116:2157-2165.
[9] G Al-Malkawi,A Hassanein.Non-equilibrium two-dimensional thermal evolutions in target materials irradiated by femtosecond laser pulse[J].Laser and Particle Beams,2014,(32):33-39.
[10] CHEN Anmin,GAO Xun,JIANG Yuanfei,et al.Numerical simulation of femtosecond laser heating of metal films using electron thermal emission[J].ACTA PHYSICA SINICA,2010,59(10):7198-7201.(in Chinese)陈安民,高勋,姜远飞,等,数值模拟飞秒激光加热金属的热电子发射[J].物理学报,2010,59(10):7198-7201.
[11] XU Bin,WU Xiaoyu,LING Shiquan,et al.Numerical simulation of thermal electron emission in metal films ablated by multi-pulse femtosecond laser[J].Laser & Optoelectronics Progress,2012,49:083201.(in Chinese)徐斌,伍晓宇,凌世全,等,多脉冲飞秒激光烧蚀金属箔的热电子发射数值分析[J].激光与光电子学进展,2012,49:083201.
[12] Sha Tao,Benxin Wu.The effect of emitted electrons during femtosecond laser-metal interactions:A physical explanation for coulomb explosion in metals[J].Appied Surface Science,2014,298:90-94.
[13] Zhaoyang Chen,Samuel S Mao.Femtosecond laser-induced electronic plasmas at metal surface[J].Applied Physics Letters,2008,93:051506.