The Nonlinear Propagation of Terahertz Wave in Plasmas

The nonlinear propagation of a terahertz wave with Gaussian beam in plasma has been investigated in this paper. The nonlinearities of pondermotive force on electron and the relativistic oscillation of the electron mass are used to study the effects on the propagation of terahertz wave in plasmas. In the present theoretical investigation, the common parabolic equation approach under the paraxial ray theory and WKB method have been adopted. Then the nonlinear differential equation for the beam-width parameter has been established and solved numerically. The numerical results show that the ponderomotive force on electron and the relativistic oscillation of the electron mass cause the periodic self-focusing/defocusing of terahertz wave. Additionally the parameteric effects on the variation of terahertz beam width parameter have been presented graphically and discussed.