Polarization property of high harmonics generated from nitrogen molecule by bichromatic counter-rotating circularly polarized laser fields

Abstract

The polarization property of high harmonics from N2 molecule is investigated in a bichromatic counter-rotating circularly polarized laser field by solving the two-dimensional time-dependent Schrödinger equation. The left- and right- circularly polarized harmonics are investigated and the results show that the helicity of the harmonic is reversed at particular harmonic orders. We also show that the electron ionized at one lobe of laser field will recombine with two different N nuclei at the same and the following laser lobes, which results in different polarization properties. The spatial distribution of the harmonic degree of circular polarization are presented to illustrate the effect on polarization properties of the electron recombined with different nuclei. The semi-classical analysis and the time-dependent probability density of electron wave packet are also demonstrated which provide a clear picture of the electron recombination process.