Surface Emitting THz Wave Parametrical Oscillator Using MgO:LiNbO

Room-temperature operation terahertz (THz) wave source is demonstrated using three MgO:LiNbO₃ crystals which have a noncollinear arrangement. The experimental results show that the THz wave can be tunable from 0.8THz to 3.0THz, and the peak energy output is 103pJ/pulse at 1.5THz. The noncollinear cavity configuration makes the THz beam have Gaussian-like spatial distribution, small divergence angle, perpendicularly eradiated from the crystal surface. The beam quality factor M² is measured to be M_x²=1.15,
M_z²=1.25 for characterizing the THz wave beam. Experiments also show that the THz beam can be focused by using a polyethylene lens, and the focal spot size is close to the diffraction limit.