Generation of twisted terahertz radiation by transferring orbital angular momentum from static plasma vortex

Here, a new scheme to create a twisted terahertz wave in a static plasma vortex is demonstrated. A static plasma vortex with a helical structure, which is submerged in the static electric field is considered. By propagating lasers in a predominant collisional nonlinearity regime, the nonlinear current density is created at the beating frequency. Based on the transfer orbital angular momentum, three schemes to excite a twisted terahertz radiation are proposed: The creation of twisted terahertz by two Laguerre-Gaussian lasers carrying different orbital angular momenta in the plasma ripple is surveyed. The helicity of terahertz radiation is provoked by the charge numbers of the lasers. In another case, the twisted terahertz generation by Laguerre-Gaussian lasers with similar orbital angular momenta in the static plasma vortex is demonstrated. Finally, even in the absence of a twisted laser, by employing the static plasma vortex, the twisted terahertz radiation can be created. In the last two cases, the helical structure of the static plasma vortex excite the orbital angular momentum of the terahertz.