Development of Cadmium Germanium Arsenide Crystals

121 Development of Cadmium Germanium Arsenide Crystals--INRAD, Inc., 181 Legrand Avenue, , Northvale, NJ 07647-2404; (201) 767-1910 Dr. Warren Ruderman, Principal Investigator Mr. James L. Greco, Business Official DOE Grant No. DE-FG02-97ER82411 Amount: $74,995 There is a need for high figure of merit nonlinear crystals for harmonic generation in the infrared and for use in optical parametric oscillators to produce continuously tunable laser radiation. CdGeAs2 single crystals have an exceptionally high nonlinear optical coefficient (351 pm/V), optical transparency from 2.5 to 16 ¿m and are phasematchable over the entire transparency range. The unavailability of large optically perfect crystals with low absorption in the fundamental transparency region has precluded the use of CdGeAs2 crystals to generate intense tunable infrared radiation. We propose to develop a crystal growth process that will yield crystals of high optical perfection. In Phase I, a synthesis process will be developed to produce pure CdGeAs2 for use as feed-stock for crystal growth. The horizontal gradient freeze technique will be explored for crystal growth. Test samples will be characterized by several methods and the results used to improve the crystal growth process. Post growth treatments will be studied to reduce optical absorption. The results of Phase I will provide the technology base for the development of a commercial process for the growth of large high optical quality CdGeAs2 single crystals. In Phase II, the crystal growth process will be scaled-up and optimized. Commercial Applications and Other Benefits as described by the awardee: CdGeAs2 crystals have important potential applications in producing tunable infrared laser radiation from 2.5 to 16 ¿m and for SHG of CO2 lasers. Applications include optical countermeasure systems, remote sensing of chemical species and contaminants in the atmosphere, and spectroscopy.