Growth of Cr:LiCaAlF6 (Cr:LiCAF) Crystals for Laser Applications

Cr:LiCAF shows potential as an efficient tunable laser with good beam quality at moderate power levels. While efficient laser operation for Cr:LiCAF has been demonstrated in the laboratory, commercialization is impeded because large crystals with low scatter loss are not available. The proposed program is to adapt the Heat Exchanger Method (HEM) for growth of Cr:LiCAF crystals. Since crystal growth by HEM is carried out wih low temperature gradients, the scattering losses in Cr:LiCAF due to defects and variation in stoichiometry are minimized. The submerged solid-liquid interface in HEM minimizes the breakdown of the interface due to the nonstiochiometric phase. The nonstoichiometric phase is rejected to the last material to solidify which is near the crucible wall. Crystal growth by HEM is achieved without moving the crucible, the heat zone, or the crystal. After growth annealing of the crystal is achieved in situ, thereby reducing defect density. This feature of HEM also allows controlled cooldown so that large crystals of Cr:LiCAF may be grown.