title: Dynamics of a paired optical vortex generated by second-harmonic generation.
abstract: We study the dynamics of a paired optical vortex (OV) generated by second-harmonic generation (SHG) using sub-picosecond pulses. By changing the position of a thin nonlinear crystal along the propagation direction, we observe a rotation of two vortices with changing separation distance. The dynamics is well explained by SHG with a beam walk-off, which introduces a contamination of zero-order Laguerre-Gaussian beam (LG(0)) together with topological charge doubling. The quantitative analysis indicates that the rotation angle of the OVs manifests the Gouy phase while the splitting provides the walk-off angle of the crystal. We also show that the subtraction of LG(0) is realized by the superposition of LG(0) with an anti-balanced phase in the pump.
authors: Department of Applied Physics, Hokkaido University, N13W8 Kita-ku, Sapporo, Japan. toda@eng.hokudai.ac.jp
authors: Y
authors: Y
authors: Toda
authors: S
authors: S
authors: Honda
authors: R
authors: R
authors: Morita
mesh_terms: D001464:Barium / Q000737:chemistry*; D001881:Borates / Q000737:chemistry*; D003461:Crystallography / Q000379:methods*; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D055095:Optics and Photonics / Q000379:methods*
chemical_list: D001881:Borates; D001464:Barium