Generation of tunable terahertz radiation by a laser pulse propagating in a magnetized plasma channel

A study of the generation of terahertz (THz) radiation by propagation of a circularly polarized laser pulse in a parabolic plasma channel is presented. The laser-plasma system is embedded in a uniform axial magnetic field. Transverse electric and magnetic wakefields are evaluated using a perturbation scheme and quasi-static approximation. Nonlinear plasma electron velocities arise along the longitudinal and transverse directions as a result of interaction with the laser pulse. This results in the generation of an electromagnetic wave oscillating at THz frequency. The frequency of the obtained THz radiation can be controlled using the plasma channel parameters and can be tuned by varying the transverse position of observation. The THz radiation amplitude is enhanced in the presence of the parabolic channel compared to the homogeneous plasma configuration. The possibility of obtaining a tunable range of THz frequencies is presented. The analytical results have been validated using three-dimensional particle-in-cell simulations.