Keywords:Terahertz, Nonlinear optics, Crystal growth
The terahertz (THz) wave has been widely applied in many fields, including medical diagnosis, high-speed communication, and nondestructive detection. The difference frequency generation (DFG) implemented with nonlinear optical crystals like GaP and GaSe can generate terahertz with high power and monochromaticity. However, the commercial GaSe crystals are grown by the Bridgman technique, which is conducted under a temperature higher than the melting point of GaSe. The defects and coexists of polytype restrict generation efficiency. In this study, the high-quality GaSe crystals have been grown from a solution whose temperature is lower than that used in the Bridgman technique. The generation efficiency increased for about ten times compared with previous results.