9361988 tsve ZnGeP2 single crystals have outstanding nonlinear and optical properties that make them the most attractive candidate for optical parametric oscillators and amplifiers capable of producing tunable laser radiation in the 2.5 to 13 um region. The development of ZnGep2 crystals has been hampered by synthesis methods that are not capable of providing the required precise stoichiometry and high purity, by an anomalous absorption between 1 and 3 um, and also by al lack of data on the pressure-temperature-composition of the Zn-Ge-P system. In Phase I we propose to use a new two-temperature synthesis to prepare ZnGeP2 samples o f varying composition above and below the exact stoichimetric point and to characterized them with respect to accurate elemental composition, optical transmission, lattice constants, resistivity and photoconductivity. An important objective will be to understand the nature of the 1 to 3 um absorption and to find out how to eliminate it.
