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. Si nce the terahertz wave is strongly absorbed inside the crystal and is affected by total internal reflection at the crystal edge, terahertz r adiation outside the crystal has been difficult. A grating coupler and a prism coupler have resulted in wide tunability, high efficiency, an d high spatial coherency. In this paper, the basic configuration of th e optical source, various radiation characteristics, and the terahertz spectroscopic system using the present source are described. (C) 1998 Scripta Technica.