title: Second harmonic generation in centrosymmetric gas with spatiotemporally focused intense femtosecond laser pulses.
abstract: We demonstrate unexpectedly strong second harmonic generation (SHG) in argon gas by use of spatio-temporally focused (SF) femtosecond laser pulses. The resulting SHG by the SF scheme at a 75 cm distance shows a significantly enhanced efficiency than that achieved with conventional focusing schemes, which offers a new promising possibility for standoff applications. Our theoretical calculations reasonably reproduce the experimental observations, which indicate that the observed SHG mainly originates from the gradient of non-uniform plasma dynamically controlled by the SF laser field.
authors.forename: Guihua
authors.initials: G
authors.lastname: Li
authors.forename: Jielei
authors.initials: J
authors.lastname: Ni
authors.forename: Hongqiang
authors.initials: H
authors.lastname: Xie
authors.forename: Bin
authors.initials: B
authors.lastname: Zeng
authors.forename: Jinping
authors.initials: J
authors.lastname: Yao
authors.forename: Wei
authors.initials: W
authors.lastname: Chu
authors.forename: Haisu
authors.initials: H
authors.lastname: Zhang
authors.forename: Chenrui
authors.initials: C
authors.lastname: Jing
authors.forename: Fei
authors.initials: F
authors.lastname: He
authors.forename: Huailiang
authors.initials: H
authors.lastname: Xu
authors.forename: Ya
authors.initials: Y
authors.lastname: Cheng
authors.forename: Zhizhan
authors.initials: Z
authors.lastname: Xu