High-order harmonics generated from single and multiple molecular orbits in mid-infrared laser fields

Jingtao Zhang
2015 Journal of Shanghai Normal University0 Natural Sciences1   unpublished
L High-order harmonics generated from aligned molecules are studied by a nonperturbative QED theory and the effect of the multiple molecular orbits is included. The harmonic spectra generated from single molecular orbit exhibit an interference minimum which is induced by the molecular structure. The location of the spectral minimum shifts with the laser intensity in long laser pulses but is fixed in ultrashort laser pulses. This difference is owed to the quiver motion of the electron in the
more » ... electron in the laser pulses. The maximal shift of the spectral minimum equals to the increment of the ponderomotive energy and depends linearly on the laser intensity. The interference between the harmonics generated from multiple molecular orbits has two principal effectss one is obscuring the deep minima in the overall harmonic spectrum the other is manifesting the phase jump in the harmonics generated from single molecular orbit. Key wordsL high-order harmonicst molecular orbtialst intense laser pulses CLC numberL O 437 Document codeL A