Multimillijoule terahertz radiation from laser interactions with microplasma waveguides

When a relativistic, femtosecond laser pulse enters waveguide, the energy is coupled into waveguide optical modes. The longitudinal field effectively accelerates electrons along axis of channel, while asymmetric transverse electromagnetic fields tend to expel fast radially outwards. At exit $\sim$${\rm nC}$, $\sim$$10\ {\rm MeV}$ electron bunch converts its mJ}$ terahertz (THz) through coherent diffraction radiation. In this paper, we present 3D particle-in-cell simulations and theoretical analyses aforementioned interaction process. We investigate process acceleration radial expulsion electrons, as well dependence properties resulting THz radiation on plasma parameters effects preplasma. simulation results indicate that conversion efficiency can be over $5\%$ if length optimal high contrast pump used. These guide design more intense powerful sources.