Growth of a New Mid-IR Laser Crystal

70606 Rare-earth-doped potassium lead pentachloride crystals are sought as new mid-IR lasers for detecting airborne chemical species for national security applications, but a reproducible growth technique is not yet available. In addition, achieving high quality crystals will also require suitable raw material preparation techniques. This project will develop purification and growth methods capable of producing the high quality crystals necessary to create efficient, diode-pumped lasers that function at important mid-IR wavelengths. The material preparation techniques of chlorination, hydrochlorination, and horizontal zone melting will be used to produce fully reacted and pure starting materials that are essential for growth of scatter-free crystals. Then, a vertical Bridgman growth method will be used to grow crystals for evaluation. In Phase I, a commercial lead chloride, which always contains some oxides and transition metal impurities, will be melted and completely chlorinated prior to being purified by zone refining. Erbium chloride will be prepared by precipitating a sol and then subjecting the material to hydrochlorination. The materials will be combined, melted together with potassium chloride, and crystalized by passing a molten zone through a sealed ampoule containing the materials. Commercial Applications and Other Benefits as described by the awardee: New lasers for detecting gaseous and biological agents should emerge from this research. The mid-IR wavelengths are in spectral regions where no other direct laser transitions exist. Commercial laser companies and defense organizations will benefit from compact, high power, diode-pumped systems.