Abstract
We report the high-efficiency THz parametric generation in 1064-nm pumped lithium niobate waveguides. By using a non-collinearly phase-matched scheme, the measured output siganl energy is 50 □J under 2.2 mJ pumping energy and the signal spectrum is from 1070.5 nm to 1072.5 nm which corresponding to THz wave with 134 □m ~ 175 □m spectrum. The conversion efficiency is as high as 2.24 % with spherical beam pump configuration in a 780-□m-thick lithium niobate. The high conversion is due to the waveguide enhancement. In addition, we compare a cylindrical-beam pumped configuration with a spherical-beam pumped one. The output terahertz-wave energy with the cylindrical-beam pumped configuration is larger than the spherical-beam pumped one under the same pump intensity. The increased aperture also allowed more pump energy into the lithium niobate crystal without any crystal damage.