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)
       
Dependence of the purity of the first principle vortex component on the laser wavelength.