High-order optical vortex harmonics generated by relativistic femtosecond laser pulse*
Han Yu-Jinga),b), Liao Guo-Qiana), Chen Li-Minga),d)†, Li Yu-Tonga),d), Wang Wei-Mina),d), Zhang Jiec),d)
       
3D structure (a) and sectional view (b) of the spiral-shaped thin foil target. (c) Initial electric field Ez of the laser pulse in the x – y plane. Plots (b) and (c) are PIC simulation results.