Creation of twisted terahertz carrying orbital angular momentum via stimulated Raman scattering in a plasma vortex

Here, a scheme for the generation of twisted terahertz radiation in a plasma vortex with a helical structure is proposed. Based on stimulated Raman scattering, the incident laser decays into the Langmuir wave. Beating the Langmuir wave with the plasma wave of the media causes the production of current density. The current density can excite twisted radiation at the terahertz frequency. For an incident laser with Gaussian envelops, the orbital angular momentum of terahertz radiation is provoked by the helicity of the plasma vortex. Furthermore, for the Laguerre–Gaussian laser, the orbital angular momentum of terahertz radiation is equal to the difference between the topological charge of the lasers and the electron plasma vortex.