Terahertz parametric oscillator with the surface-emitted configuration in RbTiOPO4 crystal

Terahertz parametric oscillator based on RbTiOPO4 (RTP) crystal utilizing the surface-emitted configuration under high pumping pulse energy and low pulse repetition rate is investigated. The obtained THz wave was discontinuously tuned from 3.01 to 3.09 THz, from 3.53 to 4.17 THz, from 4.54 to 4.66 THz, and from 5.35 to 5.89 THz, respectively. The maximum output THz wave pulse energy was 1.77 μJ at 3.85 THz. It was obtained when the pumping pulse energy was 120 mJ and the pumping beam diameter was 3.0 mm. The polarization of THz wave was along the z axis of the RTP crystal. The THz beam on its output surface was approximately elliptical with a major axis of 6.5 mm and a minor axis of 3.5 mm. The divergence angles were 2.45° in the horizontal direction, and 3.88° in the vertical direction.