A Short Review on Fluoride Laser Crystals Grown by Czochralski Method at IPEN

In this article there are presented the developments on the crystal growth by the Czochralski method of fluoride laser materials at the Center for Lasers and Applications from Institute of Nuclear and Energy Research, IPEN, Brazil. A brief report of the Czochralski furnace preparation for fluorides growth regarding to its construction materials, influence of the heating assemblies in the thermal profiles and the benefits of using a suitable atmosphere is provided. Moreover, to demonstrate the importance of this technique to the advances on laser systems over the last years there are described the specific growth conditions established to obtain fluoride crystals with suitable properties for practical application as laser hosts. $LiREF_4$ (RE = rare earth) scheelite crystals have been studied to compare $LiYF_4$ (YLF) with its isomorphs, including solid solutions of the type-$LiY_{1-x}Ln_{x}F_4$ (Ln = Gd or Lu) and $LiGd_{1-x}Lu_{x}F_4$, relating to their optical quality, spectroscopic and laser properties. Some results regarding the development of new laser hosts of these materials doped with Nd, Er, Pr and co-doped Yb, Nd and Tm are also presented. The growth particularities of transition metals doped fluoride crystals such as $BaLiF_3$:TM (TM = Ni and Co) and $LiSrAlF_6$:Cr are also reported.