Narrow linewidth terahertzgeneration from two seeded periodically poled lithium niobate optical parametric generators and applications

The terahertz (THz) or far-infrared region is a rapidly growing field with many promising applications. However, THz sources with suitable properties such as narrow linewidth and the tunability over a broad spectral range still need to be developed. Quasi-phase matched devices such as periodically poled lithium niobate (PPLN) combined with nonlinear optical devices such as optical parametric generators (OPG) represent a new generation of pump sources for generating THz outputs. This dissertation takes such an approach to generate THz radiation. A simple difference frequency generation scheme is used to mix the outputs of the two OPG's in a 4-dimethylamino-N-methy-4-stilbazolium tosylate (DAST) crystal with the resultant THz output tunable from 1.5 to 4.5 THz with a linewidth of 2.4 GHz.; The utility of this source is demonstrated by several THz measurements. We show the ability to measure water vapor in air and transmission through coatings important to the aviation industry. In another context we use the source to test new THz wave-plates based on form birefringence.; This is, to our knowledge, the first demonstration of such a waveplate in the THz region. This dissertation also includes all the theoretical analysis necessary to design the THz source and to design form birefringent THz waveplates.