Resonant X-ray second harmonic generation in atomic gases

Ji-Cai Liu (1) , Catalin Miron (2, 3, 4) , Hans Ågren (4) , Sergey Polyutov (5) , Faris Gel'Mukhanov (6)

1 North China Electric Power University
2 SSOLEIL - Synchrotron SOLEIL
3 LIDYL - Laboratoire Interactions, Dynamiques et Lasers (ex SPAM)
4 ELI-NP - Extreme Light Infrastruture - Nuclear Physics
5 SibFU - Siberian Federal University
6 Institute for Methods and Instrumentation in Synchrotron Radiation Research

We explore the x-ray second-harmonic generation process induced by resonant two-photon absorption in systems with inversion symmetry. We show that this process becomes allowed in the x-ray region due to nondipole contributions. It is found that, although a plane-wave pump field generates only a longitudinal second-harmonic field, a Gaussian pump beam creates also a radially polarized transverse second-harmonic field which is stronger than the longitudinal one. Contrary to the longitudinal component, the transverse second-harmonic field with zero intensity on the axis of the pump beam can run in free space. Our theory is applied to Ar and Ne atomic vapors and predicts an energy conversion efficiency of x-ray second-harmonic generation of 3.2 × 10−11 and 1.3 × 10−12, respectively.

Domaines: Chimie théorique et/ou physique; Mécanique des matériaux [physics.class-ph]; Chimie-Physique [physics.chem-ph]

Ji-Cai Liu, Catalin Miron, Hans Ågren, Sergey Polyutov, Faris Gel'Mukhanov. Resonant X-ray second harmonic generation in atomic gases. Physical Review A, 2019, 100 (6), ⟨10.1103/PhysRevA.100.063403⟩. ⟨hal-02442214⟩