NSF Award
9160858
Two new tunable laser materials discovered at Lawrence Livermore National Laboratory have shown intrinsic efficiency comparable to alexandrite; however, their full potential laser performance is limited by the quality of crystals available. The major impediment to the commercialization of the new laser materials is the high optical scatter loss, and cracking of crystals. The proposed program is to adapt the Heat Exchanger Method (HEMtm) for growth of the new materials. Low temperature gradients will be utilized to minimize defects and scattering losses due to variations in stoichiometry. The cracking problem is attributed to a negative thermal expansion coefficient along the C axis and stress in the crystal after growth. The shape of the solid- liquid interface during growth will be controlled such that solidification occurs off the interface in preference to off the crucible wall. In situ annealing will be carried out to minimize stress and temperature gradients on the crystal during cooldown.
