ZnGeP2 second-harmonic generator for a CO2 laser

The fabrication of high-quality single-crystal ZnGeP2 second-harmonic generators (SHG) for use in infrared CO2 lasers intended for lidar studies of trace gases in the atmosphere is described. Conditions of SHG operation at room temperature and at high temperatures are examined, and experimental results are presented for SHG crystals 10.5 and 4.5 mm thick heated up to 300 C. A stable energy conversion coefficient of about 6 percent was achieved in crystals 10.5 mm thick at temperatures of 160-190 C. The maximum conversion coefficient was 9.3 percent.