Influence of the Tilting Angle of a BBO Crystal on the Terahertz Radiation Produced by a Dual-Color Femtosecond Laser

This article studies the effect of titling a beta-barium borate (BBO) crystal on the efficiency of generating terahertz (THz) radiation by dual-color femtosecond laser filamentation. It is found that tilting the BBO crystal can compensate for the phase difference and reduce the spatial walk-off distance between the fundamental laser pulse and the second harmonic laser pulse. In increasing the intensity of the THz radiation, the method of tilting the BBO crystal is simple and complementary to the conventional method of adjusting the BBO-to-focus distance.