飞秒激光激发空气电离的阈值研究  

Determination of air ionization threshold with femtosecond laser pulses

作　　者：王晓雷[1,2] 张楠[1,2] 赵友博[1,2] 李智磊[1,2] 翟宏琛[1,2] 朱晓农[1,2] 

机构地区：[1]南开大学现代光学研究所,天津300071 [2]光电信息技术科学教育部重点实验室,天津300071

出　　处：《物理学报》2008年第1期354-357,共4页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:60377008,60637020)资助的课题~~

摘　　要：报道在脉宽50fs—22ps,波长800nm脉冲激光作用下的空气电离阈值的研究结果.利用探测等离子体发光信号的方法,实验测量了激发空气电离所需的阈值激光强度.结果表明,当激光脉冲宽度从50fs增加到22ps时,阈值光强Ith从8.7×1014W/cm2下降到2.7×1013W/cm2;Ith经历了由迅速降低逐渐发展为缓慢降低的过程.在50fs—1ps和1ps—22ps的脉宽区间,分别利用基于多光子电离和多光子电离引发的碰撞电离的理论模型的计算结果和实验结果基本一致.The intensity thresholds of air ionization induced by 800 nm ultrashort laser pulses are investigated for laser pulse durations from 50 fs to 22 ps. The intensity threshold was determined by measuring the fluorescence energy of the stimulated air ionization plasma. It is shown that as the pulse duration increases from 50 fs to 22 ps, the threshold intensity of air ionization decreases from 8.7×10^14 to 2.7×10^13 W/cm^2 and undergoes the transition from rapid decrease to slow decrease. For pulse duration shorter than 1 ps, the theoretical calculation was done based on the muhiphoton ionization and for pulse duration longer than 1 ps, the calculation was done based on the impact ionization initiated by the muhiphoton ionization. For both above cases the calculated results are in good agreement with the experiment.

关 键 词：飞秒激光 阈值 多光子电离 碰撞电离 

分 类 号：TN241[电子电信—物理电子学]