Energy scaling and extended tunability of a ring cavity terahertz parametric oscillator based on KTiOPO4 crystal
Wang Yuye1, 2, Ren Yuchen1, 2, Xu Degang1, 2, †, Tang Longhuang1, 2, He Yixin1, 2, Song Ci3, ‡, Chen Linyu1, 2, Li Changzhao1, 2, Yan Chao1, 2, Yao Jianquan1, 2
       

(color online) THz wave output voltage and light-to-light conversion efficiency under different pump energies at 5.7 THz. The inset shows the THz wavelength measurement by a scanning Fabry–Perot etalon.