Terahertz parametric oscillator with a rhombic ring-cavity.

Terahertz parametric oscillator (TPO) with a rhombic ring-cavity is demonstrated. The oscillating cavity is composed of three mirrors and the terahertz emitting-surface. Terahertz frequency can be tuned from 0.9 THz to 2.9 THz just by shifting the position of a cavity mirror. Under a certain round-trip optical length of the Stokes beam, the pump beam size can be larger in the rhombic ring-cavity TPO than that in the conventional resonant-cavity TPO. The maximum terahertz pulse energy in the rhombic ring-cavity TPO is 3.21 ÎĽ J, which is about 3 times higher than that in the conventional resonant-cavity TPO. [ABSTRACT FROM AUTHOR]