Generation and enhancement of vortex terahertz radiation through two-color lasers with different modes by Gaussian and Laguerre–Gaussian in a homogeneous plasma

The generation and enhancement of vortex terahertz radiation in the interaction of two-color Gaussian and Laguerre–Gaussian (LG) lasers with homogeneous plasmas have been investigated by theoretical analysis and particle-in-cell simulation. The analytical expression of the vortex terahertz radiation field is obtained, and the corresponding parameter regions of enhanced radiation including the beam width ratio of the LG laser to the Gaussian laser and the LG laser mode are also given. It is found that by using two-color lasers with different modes by Gaussian and LG, not only the orbital angular momentum of LG laser is successfully transferred to the radiation and the mode-controllable vortex THz is generated, but also its amplitude can be effectively enhanced than the two-color lasers with same modes by Gaussian when the appropriate LG laser mode is chosen and the beam width ratio is decreased. In particular, the relative enhancement can reach 190% when the beam width ratio α= 0.5, the LG laser mode l = 1 and p = 1 are taken in our study.