Widely tunable coherent terahertz-wave generation using nonlinear optical effect.

By using room-temperature parametric oscillation of LiNbO3 pumped by a Q-switched Nd:YAG laser, a tunable terahertz-wave source in the range between 1 and 2 THz has been realized with a simple configuration. Since the terahertz wave is strongly absorbed inside the crystal and is affected by total internal reflection at the crystal edge, terahertz radiation outside the crystal has been difficult. A grating coupler and a prism coupler have resulted in wide tunability, high efficiency, and high spatial coherency. In this paper, the basic configuration of the optical source, various radiation characteristics, and the terahertz spectroscopic system using the present source are described. © 1998 Scripta Technica, Electron Comm Jpn Pt 2, 81(7): 10–18, 1998 [ABSTRACT FROM AUTHOR]