title: Observation of non-odd order harmonics by sub-2-cycle laser pulses.
abstract: High order harmonics generation from argon gas was comprehensively investigated by using multi-cycle and few-cycle laser pulses. Non-odd order harmonics were observed for sub-5-fs pulses, compare to the normal odd-order harmonics in the multi-cycle case. Theoretic analysis shows that the new spectral structure origins from the asymmetry of laser field in few-cycle pulses. This asymmetry induced both amplitude and phase difference between attosecond pulses from consecutive half-cycle of the laser field, which change the interference property of attosecond pulses and result in complex spectrum.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Teng
authors.forename: Chen-Xia
authors.initials: CX
authors.lastname: Yun
authors.forename: Xin-Kui
authors.initials: XK
authors.lastname: He
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Li-Feng
authors.initials: LF
authors.lastname: Wang
authors.forename: Min-Jie
authors.initials: MJ
authors.lastname: Zhan
authors.forename: Bing-bing
authors.initials: BB
authors.lastname: Wang
authors.forename: Zhi-Yi
authors.initials: ZY
authors.lastname: Wei