Spectral attenuation of a 400-nm laser pulse propagating through a plasma filament induced by an intense femtosecond laser pulse  

作　　者：Quan-Jun Wang Rao Chen Jia-Chen Zhao Chun-Lin Sun Xiao-Zhen Wang Jing-Jie Ding Zuo-Ye Liu Bi-Tao Hu 王全军;陈娆;赵家琛;孙春霖;王小珍;丁晶洁;刘作业;胡碧涛(School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China;College of Chemistry and Chemical Engineering,Lanzhou University,Lanzhou 730000,China)

机构地区：[1]School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China [2]College of Chemistry and Chemical Engineering,Lanzhou University,Lanzhou 730000,China

出　　处：《Chinese Physics B》2020年第1期241-245,共5页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.U1932133,51733004,51525303,and 21702085);the Fundamental Research Funds for the Central Universities,China(Grant Nos.lzujbky-2016-35 and lzujbky-2018-it36)

摘　　要：The spectral attenuation of a 400-nm probe laser propagating through a femtosecond plasma in air is studied.Defocusing effect of the low-density plasma is an obvious effect by examining the far-field patterns of the 400-nm pulse.Besides,the energy of 400-nm pulse drops after interaction with the plasma,which is found to be another effect leading to the attenuation.To reveal the physical origin behind the energy loss,we measure fluorescence emissions of the interaction area.The fluorescence is hardly detected with the weak 400-nm laser pulse,and the line spectra from the plasma filament induced by the 800-nm pump pulse are clearly shown.However,when the 400-nm pulse propagates through the plasma filament,the fluorescence at 391 nm from the first negative band system of N2+is enhanced,while that from the second positive band of neutral N2 at 337 nm remains constant.Efficient near-resonant absorption of the 400-nm pulse by the first negative band system occurs inside the plasma,which results in the enhanced fluorescence.Furthermore,the spectral attenuation of the 400-nm probe laser is measured as a function of the pump–probe time delay as well as the pump-pulse energy.The spectral attenuation of a 400-nm probe laser propagating through a femtosecond plasma in air is studied. Defocusing effect of the low-density plasma is an obvious effect by examining the far-field patterns of the 400-nm pulse.Besides, the energy of 400-nm pulse drops after interaction with the plasma, which is found to be another effect leading to the attenuation. To reveal the physical origin behind the energy loss, we measure fluorescence emissions of the interaction area. The fluorescence is hardly detected with the weak 400-nm laser pulse, and the line spectra from the plasma filament induced by the 800-nm pump pulse are clearly shown. However, when the 400-nm pulse propagates through the plasma filament, the fluorescence at 391 nm from the first negative band system of N2+ is enhanced, while that from the second positive band of neutral N2 at 337 nm remains constant. Efficient near-resonant absorption of the 400-nm pulse by the first negative band system occurs inside the plasma, which results in the enhanced fluorescence. Furthermore, the spectral attenuation of the 400-nm probe laser is measured as a function of the pump–probe time delay as well as the pump-pulse energy.

关 键 词：defocusing effect energy loss enhanced fluorescence 

分 类 号：TN249[电子电信—物理电子学] O53[理学—等离子体物理]