Monochromatic Cherenkov THz Source Pumped by a Singly Resonant Optical Parametric Oscillator

We report an improvement of terahertz (THz) output energy via Cherenkov-type difference frequency generation by developing the dual-wavelength pump source, which is based on a singly resonant near-degenerated optical parametric oscillator. Total utilization efficiency of pump energy is considerably increased by recycling the residual fundamental wave. The highest energy of Cherenkov-type monochromatic THz generation is achieved to be 1.58 nJ/pulse. A tuning range of 0.1-3.2 THz is demonstrated.