Study on the generation of high-power terahertz wave from surface-emitted THz-wave parametric oscillator with MgO:LiNbO3 crystal

High-power nanosecond pulsed THz-wave radiation was achieved via a surface-emitted THz-wave parametric oscillator (TPO). The effective parametric gain length under the condition of noncollinear phase matching was calculated to optimize the parameters of the TPO. Only one MgO:LiNbO(3) crystal with large volume was used as gain medium. THz-wave radiation from 0.8 to 2.9 THz was obtained. The maximum THz-wave output was 289.9 nJ/pulse at 1.94 THz when pump power density was 211 MW/cm(2), corresponding to the energy conversion efficiency of 3.43x10(-6) and the photon conversion efficiency of about 0.05%. The far-field divergence angle of THz-wave radiation was 0.0204 rad at vertical direction and 0.0068 rad at horizontal direction.