Surface emitting THz wave parametrical oscillator using MgO: LiNbO3

Room-temperature operation terahertz (THz) wave source is demonstrated using three MgO:LiNbO3 crystals which have a nonlinear arrangement. The experimental results show that the THz wave can be tunable from 0.8 THz to 3.0 THz, and the peak energy output is 103 pJ/pulse at 1.5 THz. The noncollinear cavity contrifugation makes the THz beam have Gaussian-like spatial disribution, small divergence angle, perpendicularly eradiated from the crystal surface. The beam quality factor M-2 is measured to be M-x(2) = 1.15, M-z(2) = 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.