Ultrapurification, Crystal Growth, and Characterization of Rare-Earth Doped KPb2Br5 for Mid-Infared Lasers

70624 Terbium (Tb3+) doped potassium lead bromide (KPb2Br5) is a new mid-infrared (IR) laser crystal that offers low lattice phonon energy and the possibility of high doping concentrations of Tb3+-ions. Because these ions have large cross sections and excellent energy storage lifetimes, this new mid-IR laser source would greatly improve current remote sensing technology for the monitoring of nuclear explosions and other applications. This project will identify and select optimum growth conditions to produce ultrapure, high quality, large single crystals of KPb2Br5:Tb in a cost-effective way, develop pre-growth (purification) and post-growth treatments to improve the optical quality of the grown crystals, and demonstrate the feasibility of fabricating mid-infrared lasers from these crystals. In Phase I, commercially available precursor materials will be purified using zone refining, and then KPb2Br5:Tb single crystals will be grown using a modified Bridgman-Stockbarger technique. Physical, optical, and spectroscopic properties of the grown crystals will be characterized repetitively to optimize the growth conditions. The performance of the mid-IR lasers fabricated from these crystals will then be evaluated. Commercial Applications and Other Benefits as described by the awardee: The proposed KPb2Br5:Tb material would be used to fabricate compact, highly efficient room temperature mid-infrared lasers, which would find applications in remote sensing instrumentation, environmental monitoring, IR countermeasures, and molecular spectroscopic studies.