Origin of ellipticity of high-order harmonics generated by a two-color laser field in the cross-polarized configuration

S. Stremoukhov (1) , A. Andreev (1) , Boris Vodungbo (2, 3, 4) , P. Salières (5, 6) , B. Mahieu (2) , Guillaume Lambert (2)

1 Faculty of Physics [MSU, Moscow]
2 LOA - Laboratoire d'optique appliquée
3 SU - Sorbonne Université
4 LCPMR - Laboratoire de Chimie Physique - Matière et Rayonnement
5 LIDyl - Laboratoire Interactions, Dynamiques et Lasers (ex SPAM)
6 ATTO - Attophysique

Recently several techniques demonstrated the production of elliptically polarized high harmonics. One of these techniques consists of the interaction in a noble gas of two-color laser beams having orthogonal linear polarizations. Here we present the theoretical explanation of such a result observed in Lambert et al. [Nat. Commun. 6, 6167 (2015)]. Numerical calculations based on the nonperturbative light-atom interaction theory reproduce well the experimental data. The degree of polarization is analyzed for different harmonic orders and found to be high. With the help of a simplified theoretical model it is shown that the degree of harmonic ellipticity depends mainly on the population of atomic state sublevels with different angular momentum projections.

Domains: Physics [physics]

S. Stremoukhov, A. Andreev, Boris Vodungbo, P. Salières, B. Mahieu, et al.. Origin of ellipticity of high-order harmonics generated by a two-color laser field in the cross-polarized configuration. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2016, 94, pp.013855. ⟨10.1103/PhysRevA.94.013855⟩. ⟨cea-01426406⟩