Vortex and symmetric radiation character of nonlinear Thomson scattering in Laguerre-Gaussian circularly polarized laser pulses.

The radiation character of nonlinear Thomson scattering is investigated in the interaction of Lagueree-Gaussian circularly polarized laser pulses with a single electron in the angular plane. With theoretical analysis and numerical calculation, it is shown that the angular radiation distributions have annular structures with great fourfold or plane symmetry in pulses characterized by comparatively lower laser intensity (a ₀ < 6), prolonged pulse duration (τ > 50fs)or wide beam waist (b ₀ > 5μm). In other circumstances, a vortex radiation pattern is found for the first time on the basis of the electron dynamics. Further, by increasing the initial phase of laser pulse, the overall angular radiation has an interesting counter-clockwise rotating trend with a cycle of Δξ ₀  = 2π. These results would help the understanding of nonlinear Thomson scattering and push forward the research of twisted X/γ-ray generation in optical laboratory.