Absortption Reduction in Silver Thiogallate

Silver thiogallate, AgGaS2[sub], is an attractive nonlinear crystal for the generation of tunable laser radiation from 2 to 12 microns. Its application is limited by surface and bulk absorption. It is proposed to address this absorption problem by characterizing single crystals grown from off-stoichiometric Ag2[sub]S-rich solutions, as well as from conventionally grown crystals from near stoichiometric melts. both as-grown and as-annealed crystals will be characterized, particularly with respect to absorption by laser calorimetry, photoluminescence, photoconductivity, and Brewster angle spectroscopy. We expect to reveal the role of crystal imperfections, including point defects, elucidate possible mechanisms for absorption, and establish the feasibility of growing AgGaS2[sub] crystals with very low absorption.