红外与激光工程
紅外與激光工程
홍외여격광공정
INFRARED AND LASER ENGINEERING
2014年
8期
2419-2424
,共6页
双温模型%非热损伤%损伤积累%飞秒激光%单晶硅
雙溫模型%非熱損傷%損傷積纍%飛秒激光%單晶硅
쌍온모형%비열손상%손상적루%비초격광%단정규
two-temperature model%non-thermal damage%damage accumulation%femtosecond laser%crystalline silicon
理解超短激光与材料的相互作用过程与机理是开展超短激光加工等工程应用的基础。首先引入电子激发项、双光子吸收、俄歇复合项等改进双温，使其较准确地适应于飞秒激光与半导体硅材料的相互作用过程。然后，分析了热损伤效应和“非热”损伤效应的影响。最后，开展了双脉冲飞秒激光与硅的相互过程研究，并分析了电子密度、晶格温度对于损伤积累效应的影响。理论模型得到单脉冲激光损伤阈值为0.25 J/cm2，此时主要表现为热损伤；当入射能量密度大于0.53 J/cm2时，主要表现为“非热”损伤。双脉冲激光作用表明，脉冲间隔不大于100 ns(激光重频10 MHz)表现出明显的热积累效应，并显著降低损伤阈值。此时，第一个脉冲造成的电子密度升高(≤1026/m3)对损伤的贡献较小；而第一个脉冲引起的晶格温升将导致极高的电子激发以及晶格温升(≥800 K)，对损伤起主要贡献作用。该研究对于激光微加工、激光防护等领域具有参考意义。
理解超短激光與材料的相互作用過程與機理是開展超短激光加工等工程應用的基礎。首先引入電子激髮項、雙光子吸收、俄歇複閤項等改進雙溫，使其較準確地適應于飛秒激光與半導體硅材料的相互作用過程。然後，分析瞭熱損傷效應和“非熱”損傷效應的影響。最後，開展瞭雙脈遲飛秒激光與硅的相互過程研究，併分析瞭電子密度、晶格溫度對于損傷積纍效應的影響。理論模型得到單脈遲激光損傷閾值為0.25 J/cm2，此時主要錶現為熱損傷；噹入射能量密度大于0.53 J/cm2時，主要錶現為“非熱”損傷。雙脈遲激光作用錶明，脈遲間隔不大于100 ns(激光重頻10 MHz)錶現齣明顯的熱積纍效應，併顯著降低損傷閾值。此時，第一箇脈遲造成的電子密度升高(≤1026/m3)對損傷的貢獻較小；而第一箇脈遲引起的晶格溫升將導緻極高的電子激髮以及晶格溫升(≥800 K)，對損傷起主要貢獻作用。該研究對于激光微加工、激光防護等領域具有參攷意義。
리해초단격광여재료적상호작용과정여궤리시개전초단격광가공등공정응용적기출。수선인입전자격발항、쌍광자흡수、아헐복합항등개진쌍온，사기교준학지괄응우비초격광여반도체규재료적상호작용과정。연후，분석료열손상효응화“비열”손상효응적영향。최후，개전료쌍맥충비초격광여규적상호과정연구，병분석료전자밀도、정격온도대우손상적루효응적영향。이론모형득도단맥충격광손상역치위0.25 J/cm2，차시주요표현위열손상；당입사능량밀도대우0.53 J/cm2시，주요표현위“비열”손상。쌍맥충격광작용표명，맥충간격불대우100 ns(격광중빈10 MHz)표현출명현적열적루효응，병현저강저손상역치。차시，제일개맥충조성적전자밀도승고(≤1026/m3)대손상적공헌교소；이제일개맥충인기적정격온승장도치겁고적전자격발이급정격온승(≥800 K)，대손상기주요공헌작용。해연구대우격광미가공、격광방호등영역구유삼고의의。
It is the foundation for engineering, such as laser micromachining etc., of understanding ultrafast laser interaction with materials. Firstly, it was introduced with band electron excitation, Auger recombination effect and two photon excitation etc. to modify present two-temperature model to adapt for the femto-second laser interaction with silicon. Then, the damage threshold was calculated. Thermal and non -thermal damage contributions were analyzed. Finally, two -pulse laser interaction with silicon was discussed. Also, Certain important parameters such as electron density and lattice temperature influence for heat accumulation effect were compared. The laser damage fluence is about 0.25 J/cm2. At this fluence level, thermal contribution dominates damage process, which is identical to experimental findings. With a fluence more than 0.53 J/cm2 non thermal damage mechanism prevails. With two pulses shooting,the heat accumulation effect is predicted, which shows that a time span between two pulses smaller than 100 ns (corresponding to 10 MHz repetition rate) cannot be ignored and it can reduce the damage threshold significantly. It is identified an electron density after the first pulse (lower than 1026/m3) does not significantly change the heating process. However, the lattice temperature after the first pulse (higher than 800 K) can cause serious electron excitation. This research is probably valuable in laser micromachining and laser protection applications.
