Radially polarized terahertz radiation in laser-induced linear plasma wake

The radially polarized terahertz radiation from laser-induced oscillating current is investigated by employing a two-dimensions plasma wakefield analytical model. It is shown that in linear plasma wake the currents have a periodical change along laser axis, and the current directions in potential well and potential barrier are opposite. The radial currents vanish at laser axis, which is different from longitudinal current, thus leading to a angle deviation of peak radiated power of radially polarized THz wave from laser axis. The deviation is more significant in thick plasma layer. The dependance of peak radiated power and total power of THz emission on thickness of plasma layer and laser intensity is discussed.