Phase dependence of third-order harmonic generation in gases induced by two-color laser field  

作　　者：孟从森 宋盼 吕治辉 王小伟 张栋文 赵增秀 袁建民 Congsen Meng;Pan SongZhihui Lyu;Xiaowei Wang;Dongwen Zhang;Zengxiu Zhao;Jianmin Yuan(Department of Physics,National University of Defense Technology,Changsha 410073,China;Department of Physics,Graduate School of China Academy of Engineering Physics,Beijing 100193,China)

机构地区：[1]Department of Physics,National University of Defense Technology,Changsha 410073,China [2]Department of Physics,Graduate School of China Academy of Engineering Physics,Beijing 100193,China

出　　处：《Chinese Optics Letters》2023年第5期1-5,共5页中国光学快报（英文版）

基　　金：supported by the National Key Research and Development Program of China(No.2019YFA0307704);the National Natural Science Foundation of China(Nos.11974425 and 11974426);the National Safety Academic Fund(No.U1830206)。

摘　　要：We experimentally demonstrate third-harmonic generation(THG)in gases ionized by a femtosecond laser pulse superimposed on its second-harmonic(SH).The mechanism of THG has been investigated,and it demonstrates that a third-order nonlinear process dominates at low pump intensity.Asymmetric third-harmonic(TH)spectra are observed at different time delays in two color fields,which are attributed to the process of the four-wave mixing(FWM)of the broad spectrum of pump pulses.A joint measurement on the terahertz(THz)and the TH is performed.It reveals that the optimized phase for the THG jumps from 0 to 0.5πas the pump intensity increases,which is different from the THz being a constant,and indicates that the THG arises from the nonlinearity of the third-order bound electrons to the tunnel-ionization current.

关 键 词：third-harmonic generation THZ 

分 类 号：TN249[电子电信—物理电子学] O46[理学—电子物理学]